Add links in part 0 of compiler series.

Finalize draft of compilers part 0.
Add a draft of a big portion of the translation of the 0th compilers post.
2020-09-07 00:21:01 -07:00 · 2020-09-02 16:56:37 -07:00 · 2020-08-29 17:17:43 -07:00 · 2020-08-20 18:35:50 -07:00 · 2020-08-20 18:33:55 -07:00 · 2020-08-12 19:15:14 -07:00
536 changed files with 20579 additions and 19241 deletions
--- a/.gitmodules
+++ b/.gitmodules
@ -1,18 +0,0 @@
-[submodule "code/aoc-2020"]
-	path = code/aoc-2020
-	url = https://dev.danilafe.com/Advent-of-Code/AdventOfCode-2020.git
-[submodule "themes/vanilla"]
-	path = themes/vanilla
-	url = https://dev.danilafe.com/Web-Projects/vanilla-hugo.git
-[submodule "code/server-config"]
-	path = code/server-config
-	url = https://dev.danilafe.com/Nix-Configs/server-config
-[submodule "code/blog-static-flake"]
-	path = code/blog-static-flake
-	url = https://dev.danilafe.com/Nix-Configs/blog-static-flake.git
-[submodule "code/compiler"]
-	path = code/compiler
-	url = https://dev.danilafe.com/DanilaFe/bloglang.git
-[submodule "code/agda-spa"]
-	path = code/agda-spa
-	url = https://dev.danilafe.com/DanilaFe/agda-spa.git
--- a/9
+++ b/9
@ -1,9 +0,0 @@
-# frozen_string_literal: true
-
-source "https://rubygems.org"
-
-git_source(:github) {|repo_name| "https://github.com/#{repo_name}" }
-
-gem 'nokogiri'
-gem 'execjs'
-gem 'duktape'
--- a/Gemfile.lock
+++ b/Gemfile.lock
@ -1,21 +0,0 @@
-GEM
-  remote: https://rubygems.org/
-  specs:
-    duktape (2.7.0.0)
-    execjs (2.9.1)
-    mini_portile2 (2.8.6)
-    nokogiri (1.15.6)
-      mini_portile2 (~> 2.8.2)
-      racc (~> 1.4)
-    racc (1.8.0)
-
-PLATFORMS
-  ruby
-
-DEPENDENCIES
-  duktape
-  execjs
-  nokogiri
-
-BUNDLED WITH
-   2.1.4
--- a/agda.rb
+++ b/agda.rb
@ -1,343 +0,0 @@
-require "nokogiri"
-require "pathname"
-
-files = ARGV[0..-1]
-
-class LineInfo
-  attr_accessor :links
-
-  def initialize
-    @links = []
-  end
-end
-
-class AgdaContext
-  def initialize
-    @file_infos = {}
-  end
-
-  # Traverse the preformatted Agda block in the given Agda HTML file
-  # and find which textual ranges have IDs and links to other ranges.
-  # Store this information in a hash, line => LineInfo.
-  def process_agda_html_file(file)
-    return @file_infos[file] if @file_infos.include? file
-
-    @file_infos[file] = line_infos = {}
-    unless File.exists?(file)
-      return line_infos
-    end
-
-    document = Nokogiri::HTML.parse(File.open(file))
-    pre_code = document.css("pre.Agda")[0]
-
-    # The traversal postorder; we always visit children before their
-    # parents, and we visit leaves in sequence.
-    offset = 0
-    line = 1
-    pre_code.traverse do |at|
-      # Text nodes are always leaves; visiting a new leaf means we've advanced
-      # in the text by the length of that text. However, if there are newlines
-      # -- since this is a preformatted block -- we also advanced by a line.
-      # At this time, do not support links that span multiple lines, but
-      # Agda doesn't produce those either.
-      if at.text?
-        if at.content.include? "\n"
-          # This textual leaf is at least part whitespace. The logic
-          # assumes that links can't span multiple pages, and that links
-          # aren't nested, so ensure that the parent of the textual node
-          # is the preformatted block itself.
-          raise "unsupported Agda HTML output" if at.parent.name != "pre"
-
-          # Increase the line and track the final offset. Written as a loop
-          # in case we eventually want to add some handling for the pieces
-          # sandwiched between newlines.
-          at.content.split("\n", -1).each_with_index do |bit, idx|
-            line += 1 unless idx == 0
-            offset = bit.length
-          end
-        else
-          # It's not a newline node, so it could be anywhere. All we need to
-          # do is adjust the offset within the full pre block's text.
-          offset += at.content.length
-        end
-      elsif at.name == "a"
-        # We found a link. Agda emits both links and "things to link to" as
-        # 'a' nodes, so check for either, and record them. Even if
-        # the link is nested, the .content.length accessor will only
-        # retrieve the textual content, and thus -- assuming the link
-        # isn't split across lines -- will find the proper from-to range.
-
-        line_info = line_infos.fetch(line) { line_infos[line] = LineInfo.new }
-        href = at.attribute("href")
-        id = at.attribute("id")
-        if href or id
-          new_node = { :from => offset-at.content.length, :to => offset }
-          new_node[:href] = href if href
-          new_node[:id] = id if id
-
-          line_info.links << new_node
-        end
-      end
-    end
-    return line_infos
-  end
-end
-
-class FileGroup
-  def initialize(agda_context)
-    @agda_context = agda_context
-    # Agda HTML href -> list of (file, Hugo HTML node that links to it)
-    @nodes_referencing_href = {}
-    # Agda HTML href -> (its new ID in Hugo-land, file in which it's defined)
-    # This supports cross-post linking within a seires.
-    @global_seen_hrefs = {}
-    # file name -> Agda HTML href -> its new ID in Hugo-land
-    # This supports linking within a particular post.
-    @local_seen_hrefs = Hash.new { {} }
-    # Global counter to generate fresh IDs. There's no reason for it to
-    # be global within a series (since IDs are namespaced by the file they're in),
-    # but it's just more convenient this way.
-    @id_counter = 0
-  end
-
-  def note_defined_href(file, href)
-    file_hrefs = @local_seen_hrefs.fetch(file) do
-      @local_seen_hrefs[file] = {}
-    end
-
-    uniq_id = file_hrefs.fetch(href) do
-      new_id = "agda-unique-ident-#{@id_counter}"
-      @id_counter += 1
-      file_hrefs[href] = new_id
-    end
-
-    unless @global_seen_hrefs.include? href
-      @global_seen_hrefs[href] = { :file => file, :id => uniq_id }
-    end
-
-    return uniq_id
-  end
-
-  def note_used_href(file, node, href)
-    ref_list = @nodes_referencing_href.fetch(href) { @nodes_referencing_href[href] = [] }
-    ref_list << { :file => file, :node => node }
-    return href
-  end
-
-  # Given a Hugo HTML file which references potentially several Agda modules
-  # in code blocks, insert links into the code blocks.
-  #
-  # There are several things we need to take care of:
-  # 1. Finding the HTML files associated with each referenced Agda module.
-  #    For this, we make use of the data-base-path etc. attributes that
-  #    the vanilla theme inserts.
-  # 2. "zipping together" the Agda and Hugo HTML representations. Each of
-  #    them encode the code, but they use different HTML elements and structures.
-  #    So, given a Hugo HTML code block, traverse its textual contents
-  #    and find any that are covered by links in the related Agda HTML file.
-  # 3. Fixing up links: the Agda HTML links assume each module has its own HTML
-  #    file. This isn't true for us: multiple modules are stitched into
-  #    one Hugo HTML file. Also, we don't include the entire Agda HTML
-  #    file in the Hugo HTML, so some links may be broken. So, find IDs
-  #    that are visible in the Hugo file, rename them to be globally unique,
-  #    and re-write cross-file links that reference these IDs to point
-  #    inside the Hugo file.
-  def process_source_file(file, document)
-    # Process each highlight group that's been marked as an Agda file.
-    document.css('div[data-agda-block]').each do |t|
-      first_line, last_line = nil, nil
-
-      if first_line_attr = t.attribute("data-first-line")
-        first_line = first_line_attr.to_s.to_i
-      end
-      if last_line_attr = t.attribute("data-last-line")
-        last_line = last_line_attr.to_s.to_i
-      end
-
-      if first_line and last_line
-        line_range = first_line..last_line
-      else
-        line_range = 1..
-      end
-
-      full_path = t.attribute("data-file-path").to_s
-      full_path_dirs = Pathname(full_path).each_filename.to_a
-
-      # The name of an Agda module is determined from its directory
-      # structure: A/B/C.agda creates A.B.C.html. Depending on where
-      # the code is included, there might be some additional folders
-      # that precede A that we want to ignore.
-      base_path = t.attribute("data-base-path").to_s
-      base_dir_depth = 0
-      if base_path.empty?
-        # No submodules were used. Assume code/<X> is the root, since
-        # that's the code layout of the blog right now.
-        base_dir_depth = 1
-        base_path = full_path_dirs[0]
-      else
-        # The code is in a submodule. Assume that the base path / submodule
-        # root is the Agda module root, ignore all folders before that.
-        base_path_dirs = Pathname(base_path).each_filename.to_a
-        base_dir_depth = base_path_dirs.length
-      end
-
-      dirs_in_base = full_path_dirs[base_dir_depth..-1]
-      html_file = dirs_in_base.join(".").gsub(/\.agda$/, ".html")
-      html_path = File.join(["code", base_path, "html", html_file])
-
-      agda_info = @agda_context.process_agda_html_file(html_path)
-
-      # Hugo conveniently generates a bunch of spans, each encoding a line
-      # of code output. We can iterate over these and match them up with
-      # the line numbers we got from reading the Agda HTML output.
-      lines = t.css("pre.chroma code[data-lang] .line")
-      lines.zip(line_range).each do |line, line_no|
-        line_info = agda_info[line_no]
-        next unless line_info
-
-        offset = 0
-        line.traverse do |lt|
-          if lt.text?
-            content = lt.content
-            new_offset = offset + content.length
-
-            # The span/a/etc. structure of the Agda and Hugo HTML files
-            # need not line up; it's possible for there to be a single link
-            # in the Agda file that's broken up across multiple HTML nodes
-            # in the Hugo output. For now, just don't link those, since inserting
-            # such overlapping links is relatively complicated. Instead,
-            # require links to fit fully within a current text node (and thus,
-            # not overlap the boundaries of any HTML).
-            matching_links = line_info.links.filter do |link|
-              link[:from] >= offset and link[:to] <= new_offset
-            end
-
-            # A given text node can be broken into any number of sub-nodes,
-            # where some sub-nodes are still text, and others have been turned
-            # into links. Store the new pieces in replace_with. E.g.,
-            #
-            # Original:
-            #   abc
-            #
-            # New:
-            #   a<a href="..">b</a>c
-            #
-            # replace_with:
-            #   ["a", <Nokogiri::XML::Node...>, "c"]
-            #
-            # match_offset represents how much of the original text we've
-            # already converted. The below iteration assumes that matching
-            # links are in order, and don't overlap.
-            replace_with = []
-            replace_offset = 0
-            matching_links.each do |match|
-              # The link's range is an offset from the beginning of the line,
-              # but the text piece we're splitting up might be partway into
-              # the line. Convert the link coordinates to piece-relative ones.
-              relative_from = match[:from] - offset
-              relative_to = match[:to] - offset
-
-              # If the previous link ended some time before the new link
-              # began (or if the current link is the first one, and is not
-              # at the beginning), ensure that the plain text "in between"
-              # is kept.
-              replace_with << content[replace_offset...relative_from]
-
-              tag = (match.include? :href) ? 'a' : 'span'
-              new_node = Nokogiri::XML::Node.new(tag, document)
-              if match.include? :href
-                # For nodes with links, note what they're referring to, so
-                # we can adjust their hrefs when we assign global IDs.
-                href = match[:href].to_s
-                new_node['href'] = note_used_href file, new_node, href
-              end
-              if match.include? :id
-                # For nodes with IDs visible in the current Hugo file, we'll
-                # want to redirect links that previously go to other Agda
-                # module HTML files. So, note the ID that we want to redirect,
-                # and pick a new unique ID to replace it with.
-                id = match[:id].to_s
-                new_node['id'] = note_defined_href file, "#{html_file}##{id}"
-              end
-              new_node.content = content[relative_from...relative_to]
-
-              replace_with << new_node
-              replace_offset = relative_to
-            end
-            replace_with << content[replace_offset..-1]
-
-            # Finally, replace the node under consideration with the new
-            # pieces.
-            replace_with.each do |replacement|
-              lt.add_previous_sibling replacement
-            end
-            lt.remove
-
-            offset = new_offset
-          end
-        end
-      end
-    end
-  end
-
-  def cross_link_files
-    # Now, we have a complete list of all the IDs visible in scope.
-    # Redirect relevant links to these IDs. This achieves within-post
-    # links.
-    @nodes_referencing_href.each do |href, references|
-      references.each do |reference|
-        file = reference[:file]
-        node = reference[:node]
-
-        local_targets = @local_seen_hrefs[file]
-        if local_targets.include? href
-          # A code block in this fine provides this href, create a local link.
-          node['href'] = "##{local_targets[href]}"
-        elsif @global_seen_hrefs.include? href
-          # A code block in this series, but not in this file, defines
-          # this href. Create a cross-file link.
-          target = @global_seen_hrefs[href]
-          other_file = target[:file]
-          id = target[:id]
-
-          relpath = Pathname.new(other_file).dirname.relative_path_from(Pathname.new(file).dirname)
-          node['href'] = "#{relpath}##{id}"
-        else
-          # No definitions in any blog page. For now, just delete the anchor.
-          node.replace node.content
-        end
-      end
-    end
-  end
-end
-
-agda_context = AgdaContext.new
-
-file_documents = {}
-series_groups = files.group_by do |file|
-  file_documents[file] = document = Nokogiri::HTML.parse(File.open(file))
-  document.css("meta[name=blog-series]")&.attribute("content")&.to_s
-end
-
-# For the 'nil' group, process individually.
-if files_with_no_series = series_groups.delete(nil)
-  files_with_no_series.each do |file|
-    file_group = FileGroup.new agda_context
-    file_group.process_source_file file, file_documents[file]
-    file_group.cross_link_files
-  end
-end
-
-# For groups, process them together to allow cross-linking
-series_groups.each do |_, files_in_series|
-  file_group = FileGroup.new agda_context
-  files_in_series.each do |file|
-    file_group.process_source_file file, file_documents[file]
-  end
-  file_group.cross_link_files
-end
-
-# Having modified all the HTML files, save them.
-file_documents.each do |file, document|
-  File.write(file, document.to_html(encoding: 'UTF-8'))
-end
--- a/analyze.rb
+++ b/analyze.rb
@ -1,110 +0,0 @@
-require "pathname"
-require "set"
-require "json"
-
-def resolve_path(bp, p)
-  path = nil
-  if bp.start_with? "."
-    path = Pathname.new(File.join(bp, p)).cleanpath.to_s
-  elsif p.start_with? "blog/"
-    path = File.join("content", p)
-  else
-    path = File.join("content", "blog", p)
-  end
-  if File.directory? path
-    path = File.join(path, "index.md") 
-  elsif !path.end_with? ".md"
-    path += ".md"
-  end
-  path.gsub("blog/blog/", "blog/")
-end
-
-files = Set.new
-refs = {}
-Dir['content/blog/**/*.md'].each do |file|
-  file = file.chomp
-  files << file
-  arr = refs[file] || (refs[file] = [])
-  pattern = Regexp.union(/< relref "([^"]+)" >/, /< draftlink "[^"]+" "([^"]+)" >/)
-  File.open(file).read.scan(pattern) do |ref|
-    ref = resolve_path(File.dirname(file), ref[0] || ref[1])
-    arr << ref
-    files << ref
-  end
-  arr.uniq!
-end
-
-data = {}
-id = 0
-series = {}
-files.each do |file|
-  id += 1
-  name = file
-  tags = []
-  group = 1
-  draft = false
-  next unless File.exists?(file)
-  value = File.size(file)
-  url = file.gsub(/^content/, "https://danilafe.com").delete_suffix("/index.md").delete_suffix(".md")
-  File.readlines(file).each do |l|
-    if l =~ /^title: (.+)$/
-      name = $~[1].delete_prefix('"').delete_suffix('"')
-    elsif l =~ /^draft: true$/
-      draft = true
-    elsif l =~ /^series: (.+)$/
-      this_series = $~[1]
-      series_list = series.fetch(this_series) do
-        series[this_series] = []
-      end
-      series_list << file
-    elsif l =~ /^tags: (.+)$/
-      tags = $~[1].delete_prefix("[").delete_suffix("]").split(/,\s?/).map { |it| it.gsub('"', '') }
-      if tags.include? "Compilers"
-        group = 2
-      elsif tags.include? "Coq"
-        group = 3
-      elsif tags.include? "Programming Languages"
-        group = 4
-      elsif tags.include? "Haskell"
-        group = 5
-      elsif tags.include? "Crystal"
-        group = 6
-      elsif tags.include? "Agda"
-        group = 7
-      elsif tags.include? "Hugo"
-        group = 8
-      end
-    end
-  end
-  next if draft
-  data[file] = { :id => id, :name => name, :group => group, :tags => tags, :url => url, :value => value }
-end
-
-edges = []
-files.each do |file1|
-  # files.each do |file2|
-  #   next if file1 == file2
-  #   next unless data[file1][:tags].any? { |t| data[file2][:tags].include? t }
-  #   edges << { :from => data[file1][:id], :to => data[file2][:id] }
-  # end
-  next unless frefs = refs[file1]
-  frefs.each do |ref|
-    next unless data[file1]
-    next unless data[ref]
-    edges << { :from => data[file1][:id], :to => data[ref][:id] }
-  end
-end
-series.each do |series, files|
-  files.sort.each_cons(2) do |file1, file2|
-    next unless data[file1]
-    next unless data[file2]
-    edges << { :from => data[file1][:id], :to => data[file2][:id] }
-    edges << { :from => data[file2][:id], :to => data[file1][:id] }
-  end
-end
-edges.uniq!
-# edges.filter! { |e| e[:from] < e[:to] }
-edges.map! { |e| { :from => [e[:from], e[:to]].min, :to => [e[:from], e[:to]].max } }.uniq!
-
-puts ("export const nodes = " + JSON.pretty_unparse(data.values) + ";")
-puts ("export const edges = " + JSON.pretty_unparse(edges) + ";")
--- a/assets/bergamot/rendering/imp.bergamot
+++ b/assets/bergamot/rendering/imp.bergamot
@ -1,65 +0,0 @@
-LatexListNil @ latexlist(nil, nil) <-;
-LatexListCons @ latexlist(cons(?x, ?xs), cons(?l_x, ?l_s)) <- latex(?x, ?l_x), latexlist(?xs, ?l_s);
-
-IntercalateNil @ intercalate(?sep, nil, nil) <-;
-IntercalateConsCons @ intercalate(?sep, cons(?x_1, cons(?x_2, ?xs)), cons(?x_1, cons(?sep, ?ys))) <- intercalate(?sep, cons(?x_2, ?xs), ?ys);
-IntercalateConsNil @ intercalate(?sep, cons(?x, nil), cons(?x, nil)) <-;
-
-NonEmpty @ nonempty(cons(?x, ?xs)) <-;
-
-InListHere @ inlist(?e, cons(?e, ?es)) <-;
-InListThere @ inlist(?e_1, cons(?e_2, ?es)) <- inlist(?e_1, ?es);
-
-BasicParenLit @ paren(lit(?v), ?l) <- latex(lit(?v), ?l);
-BasicParenVar @ paren(var(?x), ?l) <- latex(var(?x), ?l);
-BasicParenVar @ paren(metavariable(?x), ?l) <- latex(metavariable(?x), ?l);
-BasicParenOther @ paren(?t, ?l) <- latex(?t, ?l_t), join(["(", ?l_t, ")"], ?l);
-
-LatexInt @ latex(?i, ?l) <- int(?i), tostring(?i, ?l);
-LatexFloat @ latex(?f, ?l) <- float(?f), tostring(?f, ?l);
-LatexStr @ latex(?s, ?l) <- str(?s), escapestring(?s, ?l_1), latexifystring(?s, ?l_2), join(["\\texttt{\"", ?l_2, "\"}"], ?l);
-LatexMeta @ latex(metavariable(?l), ?l) <-;
-LatexLit @ latex(lit(?i), ?l) <- latex(?i, ?l);
-LatexVar @ latex(var(metavariable(?s)), ?l) <- latex(metavariable(?s), ?l);
-LatexVar @ latex(var(?s), ?l) <- latex(?s, ?l_v), join(["\\texttt{", ?l_v, "}"], ?l);
-LatexPlus @ latex(plus(?e_1, ?e_2), ?l) <-
-    paren(?e_1, ?l_1), paren(?e_2, ?l_2),
-    join([?l_1, " + ", ?l_2], ?l);
-LatexMinus @ latex(minus(?e_1, ?e_2), ?l) <-
-    paren(?e_1, ?l_1), paren(?e_2, ?l_2),
-    join([?l_1, " - ", ?l_2], ?l);
-
-EnvLiteralNil @ envlitrec(empty, "\\{", "", ?seen) <-;
-EnvLiteralSingle @ envlitsingle(?pre, ?e, ?v, "", ?pre, ?seen) <- inlist(?e, ?seen);
-EnvLiteralSingle @ envlitsingle(?pre, ?e, ?v, ?l, ", ", ?seen) <- latex(?e, ?l_e), latex(?v, ?l_v), join([?pre, "\\texttt{", ?l_e, "} \\mapsto", ?l_v], ?l);
-EnvLiteralCons @ envlitrec(extend(empty, ?e, ?v), ?l, ?newnext, ?seen) <- envlitrec(?rho, ?l_rho, ?next, cons(?e, ?seen)), envlitsingle(?next, ?e, ?v, ?l_v, ?newnext, ?seen), join([?l_rho, ?l_v], ?l);
-EnvLiteralCons @ envlitrec(extend(?rho, ?e, ?v), ?l, ?newnext, ?seen) <- envlitrec(?rho, ?l_rho, ?next, cons(?e, ?seen)), envlitsingle(?next, ?e, ?v, ?l_v, ?newnext, ?seen), join([?l_rho, ?l_v], ?l);
-EnvLiteralOuter @ envlit(?rho, ?l) <- envlitrec(?rho, ?l_rho, ?rest, []), join([?l_rho, "\\}"], ?l);
-
-LatexEnvLit @ latex(?rho, ?l) <- envlit(?rho, ?l);
-LatexTypeEmpty @ latex(empty, "\\{\\}") <-;
-LatexExtend @ latex(extend(?a, ?b, ?c), ?l) <- latex(?a, ?l_a), latex(?b, ?l_b), latex(?c, ?l_c), join([?l_a, "[", ?l_b, " \\mapsto ", ?l_c, "]"], ?l);
-LatexInenv @ latex(inenv(?x, ?v, ?G), ?l) <-latex(?x, ?l_x), latex(?v, ?l_v), latex(?G, ?l_G), join([?l_G, "(", ?l_x, ") = ", ?l_v], ?l);
-LatexEvalTer @ latex(eval(?G, ?e, ?t), ?l) <- latex(?G, ?l_G), latex(?e, ?l_e), latex(?t, ?l_t), join([?l_G, ",\\  ", ?l_e, " \\Downarrow ", ?l_t], ?l);
-
-LatexAdd @ latex(add(?a, ?b, ?c), ?l) <- latex(?a, ?l_a), latex(?b, ?l_b), latex(?c, ?l_c), join([?l_a, "+", ?l_b, "=", ?l_c], ?l);
-LatexSubtract @ latex(subtract(?a, ?b, ?c), ?l) <- latex(?a, ?l_a), latex(?b, ?l_b), latex(?c, ?l_c), join([?l_a, "-", ?l_b, "=", ?l_c], ?l);
-LatexEvalTer @ latex(stepbasic(?G, ?e, ?H), ?l) <- latex(?G, ?l_G), latex(?e, ?l_e), latex(?H, ?l_H), join([?l_G, ",\\  ", ?l_e, " \\Rightarrow ", ?l_H], ?l);
-LatexEvalTer @ latex(step(?G, ?e, ?H), ?l) <- latex(?G, ?l_G), latex(?e, ?l_e), latex(?H, ?l_H), join([?l_G, ",\\  ", ?l_e, " \\Rightarrow ", ?l_H], ?l);
-
-LatexNoop @ latex(noop, "\\texttt{noop}") <-;
-LatexAssign @ latex(assign(?x, ?e), ?l) <- latex(?x, ?l_x), latex(?e, ?l_e), join([?l_x, " = ", ?l_e], ?l);
-LatexAssign @ latex(if(?e, ?s_1, ?s_2), ?l) <- latex(?e, ?l_e), latex(?s_1, ?l_1), latex(?s_2, ?l_2), join(["\\textbf{if}\\ ", ?l_e, "\\ \\{\\ ", ?l_1, "\\ \\}\\ \\textbf{else}\\ \\{\\ ", ?l_2, "\\ \\}"], ?l);
-LatexAssign @ latex(while(?e, ?s), ?l) <- latex(?e, ?l_e), latex(?s, ?l_s), join(["\\textbf{while}\\ ", ?l_e, "\\ \\{\\ ", ?l_s, "\\ \\}"], ?l);
-LatexAssign @ latex(seq(?s_1, ?s_2), ?l) <- latex(?s_1, ?l_1), latex(?s_2, ?l_2), join([?l_1, "; ", ?l_2], ?l);
-
-LatexNumNeq @ latex(not(eq(?e_1, ?e_2)), ?l) <- latex(?e_1, ?l_1), latex(?e_2, ?l_2), join([?l_1, " \\neq ", ?l_2], ?l);
-LatexNot @ latex(not(?e), ?l) <- latex(?e, ?l_e), join(["\\neg (", ?l_e, ")"], ?l);
-LatexNumEq @ latex(eq(?e_1, ?e_2), ?l) <- latex(?e_1, ?l_1), latex(?e_2, ?l_2), join([?l_1, " = ", ?l_2], ?l);
-
-LatexIsInt @ latex(int(?e), ?l) <- latex(?e, ?l_e), join([?l_e, " \\in \\texttt{Int}"], ?l);
-LatexIsFloat @ latex(float(?e), ?l) <- latex(?e, ?l_e), join([?l_e, " \\in \\texttt{Float}"], ?l);
-LatexIsNum @ latex(num(?e), ?l) <- latex(?e, ?l_e), join([?l_e, " \\in \\texttt{Num}"], ?l);
-LatexIsStr @ latex(str(?e), ?l) <- latex(?e, ?l_e), join([?l_e, " \\in \\texttt{Str}"], ?l);
-LatexSym @ latex(?s, ?l) <- sym(?s), tostring(?s, ?l_1), join(["\\text{", ?l_1,"}"], ?l);
-LatexCall @ latex(?c, ?l) <- call(?c, ?n, ?ts), nonempty(?ts), latexlist(?ts, ?lts_1), intercalate(", ", ?lts_1, ?lts_2), join(?lts_2, ?lts_3), join(["\\text{", ?n, "}", "(", ?lts_3, ")"], ?l);
--- a/assets/bergamot/rendering/lc.bergamot
+++ b/assets/bergamot/rendering/lc.bergamot
@ -1,74 +0,0 @@
-PrecApp @ prec(app(?l, ?r), 100, left) <-;
-PrecPlus @ prec(plus(?l, ?r), 80, either) <-;
-PrecAbs @ prec(abs(?x, ?t, ?e), 0, right) <-;
-PrecArr @ prec(tarr(?l, ?r), 0, right) <-;
-
-SelectHead @ select(cons([?t, ?v], ?rest), ?default, ?v) <- ?t;
-SelectTail @ select(cons([?t, ?v], ?rest), ?default, ?found) <- not(?t), select(?rest, ?default, ?found);
-SelectEmpty @ select(nil, ?default, ?default) <-;
-
-Eq @ eq(?x, ?x) <-;
-
-ParenthAssocLeft @ parenthassoc(?a_i, left, right) <-;
-ParenthAssocRight @ parenthassoc(?a_i, right, left) <-;
-ParenthAssocNone @ parenthassoc(?a_i, none, ?pos) <-;
-ParenthAssocNeq @ parenthassoc(?a_i, ?a_o, ?pos) <- not(eq(?a_i, ?a_o));
-
-Parenth @ parenth(?inner, ?outer, ?pos, ?strin, ?strout) <-
-    prec(?inner, ?p_i, ?a_i), prec(?outer, ?p_o, ?a_o),
-    join(["(", ?strin, ")"], ?strinparen),
-    select([ [less(?p_i, ?p_o), strinparen], [less(?p_o, ?p_i), ?strin], [ parenthassoc(?a_i, ?a_o, ?pos), ?strinparen ] ], ?strin, ?strout);
-ParenthFallback @ parenth(?inner, ?outer, ?pos, ?strin, ?strin) <-;
-
-LatexListNil @ latexlist(nil, nil) <-;
-LatexListCons @ latexlist(cons(?x, ?xs), cons(?l_x, ?l_s)) <- latex(?x, ?l_x), latexlist(?xs, ?l_s);
-
-IntercalateNil @ intercalate(?sep, nil, nil) <-;
-IntercalateConsCons @ intercalate(?sep, cons(?x_1, cons(?x_2, ?xs)), cons(?x_1, cons(?sep, ?ys))) <- intercalate(?sep, cons(?x_2, ?xs), ?ys);
-IntercalateConsNil @ intercalate(?sep, cons(?x, nil), cons(?x, nil)) <-;
-
-NonEmpty @ nonempty(cons(?x, ?xs)) <-;
-
-LatexInt @ latex(?i, ?l) <- int(?i), tostring(?i, ?l);
-LatexFloat @ latex(?f, ?l) <- float(?f), tostring(?f, ?l);
-LatexStr @ latex(?s, ?l) <- str(?s), escapestring(?s, ?l_1), latexifystring(?s, ?l_2), join(["\\texttt{\"", ?l_2, "\"}"], ?l);
-LatexMeta @ latex(metavariable(?l), ?l) <-;
-LatexLit @ latex(lit(?i), ?l) <- latex(?i, ?l);
-LatexVar @ latex(var(?s), ?l) <- latex(?s, ?l);
-LatexPlus @ latex(plus(?e_1, ?e_2), ?l) <-
-    latex(?e_1, ?l_1), latex(?e_2, ?l_2),
-    parenth(?e_1, plus(?e_1, ?e_2), left, ?l_1, ?lp_1),
-    parenth(?e_2, plus(?e_1, ?e_2), right, ?l_2, ?lp_2),
-    join([?lp_1, " + ", ?lp_2], ?l);
-LatexPair @ latex(pair(?e_1, ?e_2), ?l) <- latex(?e_1, ?l_1), latex(?e_2, ?l_2), join(["(", ?l_1, ",  ", ?l_2, ")"], ?l);
-LatexAbs @ latex(abs(?x, ?t, ?e), ?l) <- latex(?e, ?l_e), latex(?t, ?l_t), latex(?x, ?l_x), join(["\\lambda ", ?l_x, " : ", ?l_t, " . ", ?l_e], ?l);
-LatexApp @ latex(app(?e_1, ?e_2), ?l) <-
-    latex(?e_1, ?l_1), latex(?e_2, ?l_2),
-    parenth(?e_1, app(?e_1, ?e_2), left, ?l_1, ?lp_1),
-    parenth(?e_2, app(?e_1, ?e_2), right, ?l_2, ?lp_2),
-    join([?lp_1, " \\enspace ", ?lp_2], ?l);
-
-LatexTInt @ latex(tint, "\\text{tint}") <-;
-LatexTStr @ latex(tstr, "\\text{tstr}") <-;
-LatexTArr @ latex(tarr(?t_1, ?t_2), ?l) <-
-    latex(?t_1, ?l_1), latex(?t_2, ?l_2),
-    parenth(?t_1, tarr(?t_1, ?t_2), left, ?l_1, ?lp_1),
-    parenth(?t_2, tarr(?t_1, ?t_2), right, ?l_2, ?lp_2),
-    join([?lp_1, " \\to ", ?lp_2], ?l);
-LatexTPair @ latex(tpair(?t_1, ?t_2), ?l) <- latex(?t_1, ?l_1), latex(?t_2, ?l_2), join(["(", ?l_1, ", ", ?l_2, ")"], ?l);
-
-LatexTypeEmpty @ latex(empty, "\\varnothing") <-;
-LatexTypeExtend @ latex(extend(?a, ?b, ?c), ?l) <- latex(?a, ?l_a), latex(?b, ?l_b), latex(?c, ?l_c), join([?l_a, " , ", ?l_b, " : ", ?l_c], ?l);
-LatexTypeInenv @ latex(inenv(?x, ?t, ?G), ?l) <-latex(?x, ?l_x), latex(?t, ?l_t), latex(?G, ?l_G), join([?l_x, " : ", ?l_t, " \\in ", ?l_G], ?l);
-
-LatexTypeBin @ latex(type(?e, ?t), ?l) <- latex(?e, ?l_e), latex(?t, ?l_t), join([?l_e, " : ", ?l_t], ?l);
-LatexTypeTer @ latex(type(?G, ?e, ?t), ?l) <- latex(?G, ?l_G), latex(?e, ?l_e), latex(?t, ?l_t), join([?l_G, " \\vdash ", ?l_e, " : ", ?l_t], ?l);
-
-LatexConverts @ latex(converts(?f, ?t), ?l) <- latex(?f, ?l_f), latex(?t, ?l_t), join([?l_f, " \\preceq ", ?l_t], ?l);
-
-LatexIsInt @ latex(int(?e), ?l) <- latex(?e, ?l_e), join([?l_e, " \\in \\texttt{Int}"], ?l);
-LatexIsFloat @ latex(float(?e), ?l) <- latex(?e, ?l_e), join([?l_e, " \\in \\texttt{Float}"], ?l);
-LatexIsNum @ latex(num(?e), ?l) <- latex(?e, ?l_e), join([?l_e, " \\in \\texttt{Num}"], ?l);
-LatexIsStr @ latex(str(?e), ?l) <- latex(?e, ?l_e), join([?l_e, " \\in \\texttt{Str}"], ?l);
-LatexSym @ latex(?s, ?l) <- sym(?s), tostring(?s, ?l_1), join(["\\text{", ?l_1,"}"], ?l);
-LatexCall @ latex(?c, ?l) <- call(?c, ?n, ?ts), nonempty(?ts), latexlist(?ts, ?lts_1), intercalate(", ", ?lts_1, ?lts_2), join(?lts_2, ?lts_3), join(["\\text{", ?n, "}", "(", ?lts_3, ")"], ?l);
--- a/assets/scss/bergamot.scss
+++ b/assets/scss/bergamot.scss
@ -1,174 +0,0 @@
-@import "variables.scss";
-@import "mixins.scss";
-
-.bergamot-exercise {
-    counter-increment: bergamot-exercise;
-
-    .bergamot-root {
-        border: none;
-        padding: 0;
-        margin-top: 1em;
-    }
-
-
-    .bergamot-exercise-label {
-        .bergamot-exercise-number::after {
-            content: "Exercise " counter(bergamot-exercise);
-            font-weight: bold;
-            text-decoration: underline;
-        }
-    }
-
-    .bergamot-button {
-        @include bordered-block;
-        padding: 0.25em;
-        padding-left: 1em;
-        padding-right: 1em;
-        background-color: inherit;
-        display: inline-flex;
-        align-items: center;
-        justify-content: center;
-        transition: 0.25s;
-        font-family: $font-body;
-        @include var(color, text-color);
-
-        &.bergamot-hidden {
-            display: none;
-        }
-
-        .feather {
-            margin-right: 0.5em;
-        }
-    }
-
-    .bergamot-play {
-        .feather { color: $primary-color; }
-        &:hover, &:focus {
-            .feather { color: lighten($primary-color, 20%); }
-        }
-    }
-
-    .bergamot-reset {
-        .feather { color: #0099CC; }
-        &:hover, &:focus {
-            .feather { color: lighten(#0099CC, 20%); }
-        }
-
-        svg {
-            fill: none;
-        }
-    }
-
-    .bergamot-close {
-        .feather { color: tomato; }
-        &:hover, &:focus {
-            .feather { color: lighten(tomato, 20%); }
-        }
-    }
-
-    .bergamot-button-group {
-        margin-top: 1em;
-    }
-}
-
-.bergamot-root {
-    @include bordered-block;
-    padding: 1em;
-
-    .bergamot-section-heading {
-        margin-bottom: 0.5em;
-        font-family: $font-body;
-        font-style: normal;
-        font-weight: bold;
-        font-size: 1.25em;
-    }
-
-    .bergamot-section {
-        margin-bottom: 1em;
-    }
-
-    textarea {
-        display: block;
-        width: 100%;
-        height: 10em;
-        resize: none;
-    }
-
-    input[type="text"] {
-        width: 100%;
-        @include textual-input;
-    }
-
-    .bergamot-rule-list {
-        display: flex;
-        flex-direction: row;
-        flex-wrap: wrap;
-        justify-content: center;
-    }
-
-    .bergamot-rule-list katex-expression {
-        margin-left: .5em;
-        margin-right: .5em;
-        flex-grow: 1;
-        flex-basis: 0;
-    }
-
-    .bergamot-rule-section {
-        .bergamot-rule-section-name {
-            text-align: center;
-            margin: 0.25em;
-            font-weight: bold;
-        }
-    }
-
-    .bergamot-proof-tree {
-        overflow: auto;
-    }
-
-    .bergamot-error {
-        @include bordered-block;
-        padding: 0.5rem;
-        border-color: tomato;
-        background-color: rgba(tomato, 0.25);
-        margin-top: 1rem;
-    }
-
-    .bergamot-selector {
-        button {
-            @include var(background-color, background-color);
-            @include var(color, text-color);
-            @include bordered-block;
-            padding: 0.5rem;
-            font-family: $font-body;
-            border-style: dotted;
-
-            &.active {
-                border-color: $primary-color;
-                border-style: solid;
-                font-weight: bold;
-            }
-
-            &:not(:first-child) {
-                border-bottom-left-radius: 0;
-                border-top-left-radius: 0;
-            }
-
-            &:not(:last-child) {
-                border-bottom-right-radius: 0;
-                border-top-right-radius: 0;
-                border-right-width: 0;
-            }
-        }
-
-        button.active + button {
-            border-left-color: $primary-color;
-            border-left-style: solid;
-        }
-
-        margin-bottom: 1rem;
-    }
-
-    .bergamot-no-proofs {
-        text-align: center;
-    }
-}
--- a/assets/scss/donate.scss
+++ b/assets/scss/donate.scss
@ -1,56 +0,0 @@
-@import "../../themes/vanilla/assets/scss/mixins.scss";
-
-.donation-methods {
-    padding: 0;
-    border: none;
-    border-spacing: 0 0.5rem;
-
-    td {
-        padding: 0;
-        overflow: hidden;
-
-        &:first-child {
-            @include bordered-block;
-            text-align: right;
-            border-right: none;
-            border-top-right-radius: 0;
-            border-bottom-right-radius: 0;
-            padding-left: 0.5em;
-            padding-right: 0.5rem;
-
-            @include below-container-width {
-                @include bordered-block;
-                text-align: center;
-                border-bottom: none;
-                border-bottom-left-radius: 0;
-                border-bottom-right-radius: 0;
-            }
-        }
-
-        &:last-child {
-            @include bordered-block;
-            border-top-left-radius: 0;
-            border-bottom-left-radius: 0;
-
-            @include below-container-width {
-                @include bordered-block;
-                border-top-left-radius: 0;
-                border-top-right-radius: 0;
-            }
-        }
-    }
-
-    tr {
-        @include below-container-width {
-            margin-bottom: 0.5rem;
-        }
-    }
-
-    code {
-        width: 100%;
-        box-sizing: border-box;
-        border: none;
-        display: inline-block;
-        padding: 0.25rem;
-    }
-}
--- a/assets/scss/gametheory.scss
+++ b/assets/scss/gametheory.scss
@ -1,11 +0,0 @@
-@import "variables.scss";
-@import "mixins.scss";
-
-.assumption-number {
-    font-weight: bold;
-}
-
-.assumption {
-    @include bordered-block;
-    padding: 0.8rem;
-}
--- a/build-agda-html.rb
+++ b/build-agda-html.rb
@ -1,70 +0,0 @@
-require "json"
-require "set"
-require "optparse"
-require "fileutils"
-
-# For target_dir, use absolute paths because when invoking Agda, we'll be
-# using chdir.
-root_path = "code"
-target_dir = File.expand_path "code"
-data_file = "data/submodules.json"
-OptionParser.new do |opts|
-  opts.banner = "Usage: build-agda-html.rb [options]"
-
-  opts.on("--root-path=PATH", "Search for Agda project folders in the given location") do |f|
-    root_path = f
-  end
-  opts.on("--target-dir=PATH", "Generate HTML files into the given directory") do |f|
-    target_dir = File.expand_path f
-  end
-  opts.on("--data-file=FILE", "Specify the submodules.json that encodes nested submodule structure") do |f|
-    data_file = f
-  end
-end.parse!
-files = ARGV
-
-code_paths = Dir.entries(root_path).select do |f|
-  File.directory?(File.join(root_path, f)) and f != '.' and f != '..'
-end.to_set
-code_paths += JSON.parse(File.read(data_file)).keys if File.exists? data_file
-# Extending code_paths from submodules.json means that nested Agda modules
-# have their root dir correctly set.
-
-max_path = ->(path) {
-  code_paths.max_by do |code_path|
-    count = 0
-    path.chars.zip(code_path.chars) do |c1, c2|
-      break unless c1 == c2
-      count += 1
-    end
-
-    next count
-  end
-}
-
-files_for_paths = {}
-Dir.glob("**/*.agda", base: root_path) do |agda_file|
-  best_path = max_path.call(agda_file)
-  files_for_path = files_for_paths.fetch(best_path) do
-    files_for_paths[best_path] = []
-  end
-
-  files_for_path << agda_file[best_path.length + File::SEPARATOR.length..-1]
-end
-
-original_wd = Dir.getwd
-files_for_paths.each do |path, files|
-  Dir.chdir(original_wd)
-  Dir.chdir(File.join(root_path, path))
-  html_dir = File.join [target_dir, path, "html"]
-  FileUtils.mkdir_p html_dir
-
-  files.each do |file|
-    command = "#{ARGV[0]} #{file} --html --html-dir=#{html_dir}"
-    puts command
-    puts `#{command}`
-
-    # Allow some programs to fail (e.g., IO.agda in SPA without --guardedness)
-    # fail unless $? == 0
-  end
-end
--- a/code/agda-issomething/example.agda
+++ b/code/agda-issomething/example.agda
@ -1,87 +0,0 @@
-open import Agda.Primitive using (Level; lsuc)
-open import Relation.Binary.PropositionalEquality using (_≡_)
-
-variable
-    a : Level
-    A : Set a
-
-module FirstAttempt where
-    record Semigroup (A : Set a) : Set a where
-        field
-            _∙_ : A → A → A
-
-            isAssociative : ∀ (a₁ a₂ a₃ : A) → a₁ ∙ (a₂ ∙ a₃) ≡ (a₁ ∙ a₂) ∙ a₃
-
-    record Monoid (A : Set a) : Set a where
-        field semigroup : Semigroup A
-
-        open Semigroup semigroup public
-
-        field
-            zero : A
-
-            isIdentityLeft : ∀ (a : A) → zero ∙ a ≡ a
-            isIdentityRight : ∀ (a : A) → a ∙ zero ≡ a
-
-    record ContrivedExample (A : Set a) : Set a where
-        field
-            -- first property
-            monoid : Monoid A
-
-            -- second property; Semigroup is a stand-in.
-            semigroup : Semigroup A
-
-            operationsEqual : Monoid._∙_ monoid ≡ Semigroup._∙_ semigroup
-
-module SecondAttempt where
-    record IsSemigroup {A : Set a} (_∙_ : A → A → A) : Set a where
-        field isAssociative : ∀ (a₁ a₂ a₃ : A) → a₁ ∙ (a₂ ∙ a₃) ≡ (a₁ ∙ a₂) ∙ a₃
-
-    record IsMonoid {A : Set a} (zero : A) (_∙_ : A → A → A) : Set a where
-        field
-            isSemigroup : IsSemigroup _∙_
-
-            isIdentityLeft : ∀ (a : A) → zero ∙ a ≡ a
-            isIdentityRight : ∀ (a : A) → a ∙ zero ≡ a
-
-        open IsSemigroup isSemigroup public
-
-    record IsContrivedExample {A : Set a} (zero : A) (_∙_ : A → A → A) : Set a where
-        field
-            -- first property
-            monoid : IsMonoid zero _∙_
-
-            -- second property; Semigroup is a stand-in.
-            semigroup : IsSemigroup _∙_
-
-    record Semigroup (A : Set a) : Set a where
-        field
-            _∙_ : A → A → A
-            isSemigroup : IsSemigroup _∙_
-
-    record Monoid (A : Set a) : Set a where
-        field
-            zero : A
-            _∙_ : A → A → A
-            isMonoid : IsMonoid zero _∙_
-
-module ThirdAttempt {A : Set a} (_∙_ : A → A → A) where
-    record IsSemigroup : Set a where
-        field isAssociative : ∀ (a₁ a₂ a₃ : A) → a₁ ∙ (a₂ ∙ a₃) ≡ (a₁ ∙ a₂) ∙ a₃
-
-    record IsMonoid (zero : A) : Set a where
-        field
-            isSemigroup : IsSemigroup
-
-            isIdentityLeft : ∀ (a : A) → zero ∙ a ≡ a
-            isIdentityRight : ∀ (a : A) → a ∙ zero ≡ a
-
-        open IsSemigroup isSemigroup public
-
-    record IsContrivedExample (zero : A) : Set a where
-        field
-            -- first property
-            monoid : IsMonoid zero
-
-            -- second property; Semigroup is a stand-in.
-            semigroup : IsSemigroup
--- a/code/agda-spa
+++ b/code/agda-spa
@ -1 +0,0 @@
-Subproject commit 828b652d3b9266e27ef7cf5a8a7fb82e3fd3133f
--- a/code/aoc-2020
+++ b/code/aoc-2020
@ -1 +0,0 @@
-Subproject commit 7a8503c3fe1aa7e624e4d8672aa9b56d24b4ba82
--- a/code/blog-static-flake
+++ b/code/blog-static-flake
@ -1 +0,0 @@
-Subproject commit 67b47d9c298e7476c2ca211aac5c5fd961637b7b
--- a/code/catamorphisms/Cata.hs
+++ b/code/catamorphisms/Cata.hs
@ -1,112 +0,0 @@
-{-# LANGUAGE LambdaCase, DeriveFunctor, DeriveFoldable, MultiParamTypeClasses #-}
-import Prelude hiding (length, sum, fix)
-
-length :: [a] -> Int
-length [] = 0
-length (_:xs) = 1 + length xs
-
-lengthF :: ([a] -> Int) -> [a] -> Int
-lengthF rec [] = 0
-lengthF rec (_:xs) = 1 + rec xs
-
-lengthF' = \rec -> \case
-    [] -> 0
-    _:xs -> 1 + rec xs
-
-fix f = let x = f x in x
-
-length' = fix lengthF
-
-data MyList = MyNil | MyCons Int MyList
-data MyListF a = MyNilF | MyConsF Int a 
-
-newtype Fix f = Fix { unFix :: f (Fix f) }
-
-testList :: Fix MyListF
-testList = Fix (MyConsF 1 (Fix (MyConsF 2 (Fix (MyConsF 3 (Fix MyNilF))))))
-
-myOut :: MyList -> MyListF MyList
-myOut MyNil = MyNilF
-myOut (MyCons i xs) = MyConsF i xs
-
-myIn :: MyListF MyList -> MyList 
-myIn MyNilF = MyNil
-myIn (MyConsF i xs) = MyCons i xs
-
-instance Functor MyListF where
-    fmap f MyNilF = MyNilF
-    fmap f (MyConsF i a) = MyConsF i (f a)
-
-mySumF :: MyListF Int -> Int
-mySumF MyNilF = 0
-mySumF (MyConsF i rest) = i + rest
-
-mySum :: MyList -> Int
-mySum = mySumF . fmap mySum . myOut
-
-myCata :: (MyListF a -> a) -> MyList -> a
-myCata f = f . fmap (myCata f) . myOut
-
-myLength = myCata $ \case
-    MyNilF -> 0
-    MyConsF _ l -> 1 + l
-
-myMax = myCata $ \case
-    MyNilF -> 0
-    MyConsF x y -> max x y
-
-myMin = myCata $ \case
-    MyNilF -> 0
-    MyConsF x y -> min x y
-
-myTestList = MyCons 2 (MyCons 1 (MyCons 3 MyNil))
-
-pack :: a -> (Int -> a -> a) -> MyListF a -> a
-pack b f MyNilF = b
-pack b f (MyConsF x y) = f x y
-
-unpack :: (MyListF a -> a) -> (a, Int -> a -> a)
-unpack f = (f MyNilF, \i a -> f (MyConsF i a))
-
-class Functor f => Cata a f where
-    out :: a -> f a
-
-cata :: Cata a f => (f b -> b) -> a -> b
-cata f = f . fmap (cata f) . out
-
-instance Cata MyList MyListF where
-    out = myOut
-
-data ListF a b = Nil | Cons a b deriving Functor
-
-instance Cata [a] (ListF a) where
-    out [] = Nil
-    out (x:xs) = Cons x xs
-
-sum :: Num a => [a] -> a
-sum = cata $ \case
-    Nil -> 0
-    Cons x xs -> x + xs
-
-data BinaryTree a = Node a (BinaryTree a) (BinaryTree a) | Leaf deriving (Show, Foldable)
-data BinaryTreeF a b = NodeF a b b | LeafF deriving Functor
-
-instance Cata (BinaryTree a) (BinaryTreeF a) where
-    out (Node a l r) = NodeF a l r
-    out Leaf = LeafF
-
-invert :: BinaryTree a -> BinaryTree a
-invert = cata $ \case
-    LeafF -> Leaf
-    NodeF a l r -> Node a r l
-
-data MaybeF a b = NothingF | JustF a deriving Functor
-
-instance Cata (Maybe a) (MaybeF a) where
-    out Nothing = NothingF
-    out (Just x) = JustF x
-
-getOrDefault :: a -> Maybe a -> a
-getOrDefault d = cata $ \case
-    NothingF -> d
-    JustF a -> a
--- a/code/compiler
+++ b/code/compiler
@ -1 +0,0 @@
-Subproject commit 137455b0f4365ba3fd11c45ce49781cdbe829ec3
--- a/code/compiler/01/scanner.l
+++ b/code/compiler/01/scanner.l
@ -0,0 +1,33 @@
+%option noyywrap
+
+%{
+#include <iostream>
+%}
+
+%%
+
+[ \n]+ {}
+\+ { std::cout << "PLUS" << std::endl; }
+\* { std::cout << "TIMES" << std::endl; }
+- { std::cout << "MINUS" << std::endl; }
+\/ { std::cout << "DIVIDE" << std::endl; }
+[0-9]+ { std::cout << "NUMBER: " << yytext << std::endl; }
+defn { std::cout << "KEYWORD: defn" << std::endl; }
+data { std::cout << "KEYWORD: data" << std::endl; }
+case { std::cout << "KEYWORD: case" << std::endl; }
+of { std::cout << "KEYWORD: of" << std::endl; }
+\{ { std::cout << "OPEN CURLY" << std::endl; }
+\} { std::cout << "CLOSED CURLY" << std::endl; }
+\( { std::cout << "OPEN PARENTH" << std::endl; }
+\) { std::cout << "CLOSE PARENTH" << std::endl; }
+,  { std::cout << "COMMA" << std::endl; }
+-> { std::cout << "PATTERN ARROW" << std::endl; }
+= { std::cout << "EQUAL" << std::endl; }
+[a-z][a-zA-Z]* { std::cout << "LOWERCASE IDENTIFIER: " << yytext << std::endl; }
+[A-Z][a-zA-Z]* { std::cout << "UPPERCASE IDENTIFIER: " << yytext << std::endl; }
+
+%%
+
+int main() {
+    yylex();
+}
--- a/code/compiler/02/ast.hpp
+++ b/code/compiler/02/ast.hpp
@ -0,0 +1,128 @@
+#pragma once
+#include <memory>
+#include <vector>
+
+struct ast {
+    virtual ~ast() = default;
+};
+
+using ast_ptr = std::unique_ptr<ast>;
+
+struct pattern {
+    virtual ~pattern() = default;
+};
+
+using pattern_ptr = std::unique_ptr<pattern>;
+
+struct branch {
+    pattern_ptr pat;
+    ast_ptr expr;
+
+    branch(pattern_ptr p, ast_ptr a)
+        : pat(std::move(p)), expr(std::move(a)) {}
+};
+
+using branch_ptr = std::unique_ptr<branch>;
+
+struct constructor {
+    std::string name;
+    std::vector<std::string> types;
+
+    constructor(std::string n, std::vector<std::string> ts)
+        : name(std::move(n)), types(std::move(ts)) {}
+};
+
+using constructor_ptr = std::unique_ptr<constructor>;
+
+struct definition {
+    virtual ~definition() = default;
+};
+
+using definition_ptr = std::unique_ptr<definition>;
+
+enum binop {
+    PLUS,
+    MINUS,
+    TIMES,
+    DIVIDE
+};
+
+struct ast_int : public ast {
+    int value;
+
+    explicit ast_int(int v)
+        : value(v) {}
+};
+
+struct ast_lid : public ast {
+    std::string id;
+
+    explicit ast_lid(std::string i)
+        : id(std::move(i)) {}
+};
+
+struct ast_uid : public ast {
+    std::string id;
+
+    explicit ast_uid(std::string i)
+        : id(std::move(i)) {}
+};
+
+struct ast_binop : public ast {
+    binop op;  
+    ast_ptr left;
+    ast_ptr right;
+
+    ast_binop(binop o, ast_ptr l, ast_ptr r)
+        : op(o), left(std::move(l)), right(std::move(r)) {}
+};
+
+struct ast_app : public ast {
+    ast_ptr left;
+    ast_ptr right;
+
+    ast_app(ast_ptr l, ast_ptr r)
+        : left(std::move(l)), right(std::move(r)) {}
+};
+
+struct ast_case : public ast {
+    ast_ptr of;
+    std::vector<branch_ptr> branches;
+
+    ast_case(ast_ptr o, std::vector<branch_ptr> b)
+        : of(std::move(o)), branches(std::move(b)) {}
+};
+
+struct pattern_var : public pattern {
+    std::string var;
+
+    pattern_var(std::string v)
+        : var(std::move(v)) {}
+};
+
+struct pattern_constr : public pattern {
+    std::string constr;
+    std::vector<std::string> params;
+
+    pattern_constr(std::string c, std::vector<std::string> p)
+        : constr(std::move(c)), params(std::move(p)) {}
+};
+
+struct definition_defn : public definition {
+    std::string name;
+    std::vector<std::string> params;
+    ast_ptr body;
+
+    definition_defn(std::string n, std::vector<std::string> p, ast_ptr b)
+        : name(std::move(n)), params(std::move(p)), body(std::move(b)) {
+
+    }
+};
+
+struct definition_data : public definition {
+    std::string name;
+    std::vector<constructor_ptr> constructors;
+
+    definition_data(std::string n, std::vector<constructor_ptr> cs)
+        : name(std::move(n)), constructors(std::move(cs)) {}
+};
--- a/code/compiler/02/clean.sh
+++ b/code/compiler/02/clean.sh
@ -0,0 +1 @@
+rm -f parser.o parser.cpp parser.hpp stack.hh scanner.cpp scanner.o a.out
--- a/code/compiler/02/compile.sh
+++ b/code/compiler/02/compile.sh
@ -0,0 +1,5 @@
+bison -o parser.cpp -d parser.y
+flex -o scanner.cpp scanner.l
+g++ -c -o scanner.o scanner.cpp
+g++ -c -o parser.o parser.cpp
+g++ main.cpp parser.o scanner.o
--- a/code/compiler/02/main.cpp
+++ b/code/compiler/02/main.cpp
@ -0,0 +1,14 @@
+#include "ast.hpp"
+#include "parser.hpp"
+
+void yy::parser::error(const std::string& msg) {
+    std::cout << "An error occured: " << msg << std::endl;
+}
+
+extern std::vector<definition_ptr> program;
+
+int main() {
+    yy::parser parser;
+    parser.parse();
+    std::cout << program.size() << std::endl;
+}
--- a/code/compiler/02/parser.y
+++ b/code/compiler/02/parser.y
@ -0,0 +1,140 @@
+%{
+#include <string>
+#include <iostream>
+#include "ast.hpp"
+#include "parser.hpp"
+
+std::vector<definition_ptr> program;
+extern yy::parser::symbol_type yylex();
+
+%}
+
+%token PLUS
+%token TIMES
+%token MINUS
+%token DIVIDE
+%token <int> INT
+%token DEFN
+%token DATA
+%token CASE
+%token OF
+%token OCURLY
+%token CCURLY
+%token OPAREN
+%token CPAREN
+%token COMMA
+%token ARROW
+%token EQUAL
+%token <std::string> LID
+%token <std::string> UID
+
+%language "c++"
+%define api.value.type variant
+%define api.token.constructor
+
+%type <std::vector<std::string>> lowercaseParams uppercaseParams
+%type <std::vector<definition_ptr>> program definitions
+%type <std::vector<branch_ptr>> branches
+%type <std::vector<constructor_ptr>> constructors
+%type <ast_ptr> aAdd aMul case app appBase
+%type <definition_ptr> definition defn data 
+%type <branch_ptr> branch
+%type <pattern_ptr> pattern
+%type <constructor_ptr> constructor
+
+%start program
+
+%%
+
+program
+    : definitions { program = std::move($1); }
+    ;
+
+definitions
+    : definitions definition { $$ = std::move($1); $$.push_back(std::move($2)); }
+    | definition { $$ = std::vector<definition_ptr>(); $$.push_back(std::move($1)); }
+    ;
+
+definition
+    : defn { $$ = std::move($1); }
+    | data { $$ = std::move($1); }
+    ;
+
+defn
+    : DEFN LID lowercaseParams EQUAL OCURLY aAdd CCURLY
+        { $$ = definition_ptr(
+            new definition_defn(std::move($2), std::move($3), std::move($6))); }
+    ;
+
+lowercaseParams
+    : %empty { $$ = std::vector<std::string>(); }
+    | lowercaseParams LID { $$ = std::move($1); $$.push_back(std::move($2)); }
+    ;
+
+uppercaseParams
+    : %empty { $$ = std::vector<std::string>(); }
+    | uppercaseParams UID { $$ = std::move($1); $$.push_back(std::move($2)); }
+    ;
+
+aAdd
+    : aAdd PLUS aMul { $$ = ast_ptr(new ast_binop(PLUS, std::move($1), std::move($3))); }
+    | aAdd MINUS aMul { $$ = ast_ptr(new ast_binop(MINUS, std::move($1), std::move($3))); }
+    | aMul { $$ = std::move($1); }
+    ;
+
+aMul
+    : aMul TIMES app { $$ = ast_ptr(new ast_binop(TIMES, std::move($1), std::move($3))); }
+    | aMul DIVIDE app { $$ = ast_ptr(new ast_binop(DIVIDE, std::move($1), std::move($3))); }
+    | app { $$ = std::move($1); }
+    ;
+
+app
+    : app appBase { $$ = ast_ptr(new ast_app(std::move($1), std::move($2))); }
+    | appBase { $$ = std::move($1); }
+    ;
+
+appBase
+    : INT { $$ = ast_ptr(new ast_int($1)); }
+    | LID { $$ = ast_ptr(new ast_lid(std::move($1))); }
+    | UID { $$ = ast_ptr(new ast_uid(std::move($1))); }
+    | OPAREN aAdd CPAREN { $$ = std::move($2); }
+    | case { $$ = std::move($1); }
+    ;
+
+case
+    : CASE aAdd OF OCURLY branches CCURLY 
+        { $$ = ast_ptr(new ast_case(std::move($2), std::move($5))); }
+    ;
+
+branches
+    : branches branch { $$ = std::move($1); $1.push_back(std::move($2)); }
+    | branch { $$ = std::vector<branch_ptr>(); $$.push_back(std::move($1));}
+    ;
+
+branch
+    : pattern ARROW OCURLY aAdd CCURLY
+        { $$ = branch_ptr(new branch(std::move($1), std::move($4))); }
+    ;
+
+pattern
+    : LID { $$ = pattern_ptr(new pattern_var(std::move($1))); }
+    | UID lowercaseParams
+        { $$ = pattern_ptr(new pattern_constr(std::move($1), std::move($2))); }
+    ;
+
+data
+    : DATA UID EQUAL OCURLY constructors CCURLY
+        { $$ = definition_ptr(new definition_data(std::move($2), std::move($5))); }
+    ;
+
+constructors
+    : constructors COMMA constructor { $$ = std::move($1); $$.push_back(std::move($3)); }
+    | constructor
+        { $$ = std::vector<constructor_ptr>(); $$.push_back(std::move($1)); }
+    ;
+
+constructor
+    : UID uppercaseParams
+        { $$ = constructor_ptr(new constructor(std::move($1), std::move($2))); }
+    ;
+
--- a/code/compiler/02/scanner.l
+++ b/code/compiler/02/scanner.l
@ -0,0 +1,34 @@
+%option noyywrap
+
+%{
+#include <iostream>
+#include "ast.hpp"
+#include "parser.hpp"
+
+#define YY_DECL yy::parser::symbol_type yylex()
+
+%}
+
+%%
+
+[ \n]+ {}
+\+ { return yy::parser::make_PLUS(); }
+\* { return yy::parser::make_TIMES(); }
+- { return yy::parser::make_MINUS(); }
+\/ { return yy::parser::make_DIVIDE(); }
+[0-9]+ { return yy::parser::make_INT(atoi(yytext)); }
+defn { return yy::parser::make_DEFN(); }
+data { return yy::parser::make_DATA(); }
+case { return yy::parser::make_CASE(); }
+of { return yy::parser::make_OF(); }
+\{ { return yy::parser::make_OCURLY(); }
+\} { return yy::parser::make_CCURLY(); }
+\( { return yy::parser::make_OPAREN(); }
+\) { return yy::parser::make_CPAREN(); }
+,  { return yy::parser::make_COMMA(); }
+-> { return yy::parser::make_ARROW(); }
+= { return yy::parser::make_EQUAL(); }
+[a-z][a-zA-Z]* { return yy::parser::make_LID(std::string(yytext)); }
+[A-Z][a-zA-Z]* { return yy::parser::make_UID(std::string(yytext)); }
+
+%%
--- a/code/compiler/03/ast.cpp
+++ b/code/compiler/03/ast.cpp
@ -0,0 +1,82 @@
+#include "ast.hpp"
+
+std::string op_name(binop op) {
+    switch(op) {
+        case PLUS: return "+";
+        case MINUS: return "-";
+        case TIMES: return "*";
+        case DIVIDE: return "/";
+    }
+    throw 0;
+}
+
+type_ptr ast_int::typecheck(type_mgr& mgr, const type_env& env) const {
+    return type_ptr(new type_base("Int"));
+}
+
+type_ptr ast_lid::typecheck(type_mgr& mgr, const type_env& env) const {
+    return env.lookup(id);
+}
+
+type_ptr ast_uid::typecheck(type_mgr& mgr, const type_env& env) const {
+    return env.lookup(id);
+}
+
+type_ptr ast_binop::typecheck(type_mgr& mgr, const type_env& env) const {
+    type_ptr ltype = left->typecheck(mgr, env);
+    type_ptr rtype = right->typecheck(mgr, env);
+    type_ptr ftype = env.lookup(op_name(op));
+    if(!ftype) throw 0;
+
+    type_ptr return_type = mgr.new_type();
+    type_ptr arrow_one = type_ptr(new type_arr(rtype, return_type));
+    type_ptr arrow_two = type_ptr(new type_arr(ltype, arrow_one));
+
+    mgr.unify(arrow_two, ftype);
+    return return_type;
+}
+
+type_ptr ast_app::typecheck(type_mgr& mgr, const type_env& env) const {
+    type_ptr ltype = left->typecheck(mgr, env);
+    type_ptr rtype = right->typecheck(mgr, env);
+
+    type_ptr return_type = mgr.new_type();
+    type_ptr arrow = type_ptr(new type_arr(rtype, return_type));
+    mgr.unify(arrow, ltype);
+    return return_type;
+}
+
+type_ptr ast_case::typecheck(type_mgr& mgr, const type_env& env) const {
+    type_ptr case_type = of->typecheck(mgr, env);
+    type_ptr branch_type = mgr.new_type();
+
+    for(auto& branch : branches) {
+        type_env new_env = env.scope();
+        branch->pat->match(case_type, mgr, new_env);
+        type_ptr curr_branch_type = branch->expr->typecheck(mgr, new_env);
+        mgr.unify(branch_type, curr_branch_type);
+    }
+
+    return branch_type;
+}
+
+void pattern_var::match(type_ptr t, type_mgr& mgr, type_env& env) const {
+    env.bind(var, t);
+}
+
+void pattern_constr::match(type_ptr t, type_mgr& mgr, type_env& env) const {
+    type_ptr constructor_type = env.lookup(constr);
+    if(!constructor_type) throw 0;
+
+    for(int i = 0; i < params.size(); i++) {
+        type_arr* arr = dynamic_cast<type_arr*>(constructor_type.get());
+        if(!arr) throw 0;
+
+        env.bind(params[i], arr->left);
+        constructor_type = arr->right;
+    }
+
+    mgr.unify(t, constructor_type);
+    type_base* result_type = dynamic_cast<type_base*>(constructor_type.get());
+    if(!result_type) throw 0;
+}
--- a/code/compiler/03/ast.hpp
+++ b/code/compiler/03/ast.hpp
@ -0,0 +1,162 @@
+#pragma once
+#include <memory>
+#include <vector>
+#include "type.hpp"
+#include "env.hpp"
+
+struct ast {
+    virtual ~ast() = default;
+
+    virtual type_ptr typecheck(type_mgr& mgr, const type_env& env) const = 0;
+};
+
+using ast_ptr = std::unique_ptr<ast>;
+
+struct pattern {
+    virtual ~pattern() = default;
+
+    virtual void match(type_ptr t, type_mgr& mgr, type_env& env) const = 0;
+};
+
+using pattern_ptr = std::unique_ptr<pattern>;
+
+struct branch {
+    pattern_ptr pat;
+    ast_ptr expr;
+
+    branch(pattern_ptr p, ast_ptr a)
+        : pat(std::move(p)), expr(std::move(a)) {}
+};
+
+using branch_ptr = std::unique_ptr<branch>;
+
+struct constructor {
+    std::string name;
+    std::vector<std::string> types;
+
+    constructor(std::string n, std::vector<std::string> ts)
+        : name(std::move(n)), types(std::move(ts)) {}
+};
+
+using constructor_ptr = std::unique_ptr<constructor>;
+
+struct definition {
+    virtual ~definition() = default;
+    
+    virtual void typecheck_first(type_mgr& mgr, type_env& env) = 0;
+    virtual void typecheck_second(type_mgr& mgr, const type_env& env) const = 0;
+};
+
+using definition_ptr = std::unique_ptr<definition>;
+
+enum binop {
+    PLUS,
+    MINUS,
+    TIMES,
+    DIVIDE
+};
+
+struct ast_int : public ast {
+    int value;
+
+    explicit ast_int(int v)
+        : value(v) {}
+
+    type_ptr typecheck(type_mgr& mgr, const type_env& env) const;
+};
+
+struct ast_lid : public ast {
+    std::string id;
+
+    explicit ast_lid(std::string i)
+        : id(std::move(i)) {}
+
+    type_ptr typecheck(type_mgr& mgr, const type_env& env) const;
+};
+
+struct ast_uid : public ast {
+    std::string id;
+
+    explicit ast_uid(std::string i)
+        : id(std::move(i)) {}
+
+    type_ptr typecheck(type_mgr& mgr, const type_env& env) const;
+};
+
+struct ast_binop : public ast {
+    binop op;  
+    ast_ptr left;
+    ast_ptr right;
+
+    ast_binop(binop o, ast_ptr l, ast_ptr r)
+        : op(o), left(std::move(l)), right(std::move(r)) {}
+
+    type_ptr typecheck(type_mgr& mgr, const type_env& env) const;
+};
+
+struct ast_app : public ast {
+    ast_ptr left;
+    ast_ptr right;
+
+    ast_app(ast_ptr l, ast_ptr r)
+        : left(std::move(l)), right(std::move(r)) {}
+
+    type_ptr typecheck(type_mgr& mgr, const type_env& env) const;
+};
+
+struct ast_case : public ast {
+    ast_ptr of;
+    std::vector<branch_ptr> branches;
+
+    ast_case(ast_ptr o, std::vector<branch_ptr> b)
+        : of(std::move(o)), branches(std::move(b)) {}
+
+    type_ptr typecheck(type_mgr& mgr, const type_env& env) const;
+};
+
+struct pattern_var : public pattern {
+    std::string var;
+
+    pattern_var(std::string v)
+        : var(std::move(v)) {}
+
+    void match(type_ptr t, type_mgr& mgr, type_env& env) const;
+};
+
+struct pattern_constr : public pattern {
+    std::string constr;
+    std::vector<std::string> params;
+
+    pattern_constr(std::string c, std::vector<std::string> p)
+        : constr(std::move(c)), params(std::move(p)) {}
+
+    void match(type_ptr t, type_mgr&, type_env& env) const;
+};
+
+struct definition_defn : public definition {
+    std::string name;
+    std::vector<std::string> params;
+    ast_ptr body;
+
+    type_ptr return_type;
+    std::vector<type_ptr> param_types;
+
+    definition_defn(std::string n, std::vector<std::string> p, ast_ptr b)
+        : name(std::move(n)), params(std::move(p)), body(std::move(b)) {
+
+    }
+
+    void typecheck_first(type_mgr& mgr, type_env& env);
+    void typecheck_second(type_mgr& mgr, const type_env& env) const;
+};
+
+struct definition_data : public definition {
+    std::string name;
+    std::vector<constructor_ptr> constructors;
+
+    definition_data(std::string n, std::vector<constructor_ptr> cs)
+        : name(std::move(n)), constructors(std::move(cs)) {}
+
+    void typecheck_first(type_mgr& mgr, type_env& env);
+    void typecheck_second(type_mgr& mgr, const type_env& env) const;
+};
--- a/code/compiler/03/bad1.txt
+++ b/code/compiler/03/bad1.txt
@ -0,0 +1,2 @@
+data Bool = { True, False }
+defn main = { 3 + True }
--- a/code/compiler/03/bad2.txt
+++ b/code/compiler/03/bad2.txt
@ -0,0 +1 @@
+defn main = { 1 2 3 4 5 }
--- a/code/compiler/03/clean.sh
+++ b/code/compiler/03/clean.sh
@ -0,0 +1 @@
+rm -f parser.o parser.cpp parser.hpp stack.hh scanner.cpp scanner.o type.o env.o ast.o definition.o a.out
--- a/code/compiler/03/compile.sh
+++ b/code/compiler/03/compile.sh
@ -0,0 +1,9 @@
+bison -o parser.cpp -d parser.y
+flex -o scanner.cpp scanner.l
+g++ -g -c -o scanner.o scanner.cpp
+g++ -g -c -o parser.o parser.cpp
+g++ -g -c -o type.o type.cpp
+g++ -g -c -o env.o env.cpp
+g++ -g -c -o ast.o ast.cpp
+g++ -g -c -o definition.o definition.cpp
+g++ -g main.cpp parser.o scanner.o type.o env.o ast.o definition.o
--- a/code/compiler/03/definition.cpp
+++ b/code/compiler/03/definition.cpp
@ -0,0 +1,48 @@
+#include "ast.hpp"
+
+void definition_defn::typecheck_first(type_mgr& mgr, type_env& env) {
+    return_type = mgr.new_type();
+    type_ptr full_type = return_type;
+
+    for(auto it = params.rbegin(); it != params.rend(); it++) {
+        type_ptr param_type = mgr.new_type();
+        full_type = type_ptr(new type_arr(param_type, full_type));
+        param_types.push_back(param_type);
+    }
+
+    env.bind(name, full_type);
+}
+
+void definition_defn::typecheck_second(type_mgr& mgr, const type_env& env) const {
+    type_env new_env = env.scope();
+    auto param_it = params.begin();
+    auto type_it = param_types.rbegin();
+
+    while(param_it != params.end() && type_it != param_types.rend()) {
+        new_env.bind(*param_it, *type_it);
+        param_it++;
+        type_it++;
+    }
+
+    type_ptr body_type = body->typecheck(mgr, new_env);
+    mgr.unify(return_type, body_type);
+}
+
+void definition_data::typecheck_first(type_mgr& mgr, type_env& env) {
+    type_ptr return_type = type_ptr(new type_base(name));
+
+    for(auto& constructor : constructors) {
+        type_ptr full_type = return_type;
+
+        for(auto& type_name : constructor->types) {
+            type_ptr type = type_ptr(new type_base(type_name));
+            full_type = type_ptr(new type_arr(type, full_type));
+        }
+
+        env.bind(constructor->name, full_type);
+    }
+}
+
+void definition_data::typecheck_second(type_mgr& mgr, const type_env& env) const {
+    // Nothing
+}
--- a/code/compiler/03/env.cpp
+++ b/code/compiler/03/env.cpp
@ -0,0 +1,16 @@
+#include "env.hpp"
+
+type_ptr type_env::lookup(const std::string& name) const {
+    auto it = names.find(name);
+    if(it != names.end()) return it->second;
+    if(parent) return parent->lookup(name);
+    return nullptr;
+}
+
+void type_env::bind(const std::string& name, type_ptr t) {
+    names[name] = t;
+}
+
+type_env type_env::scope() const {
+    return type_env(this);
+}
--- a/code/compiler/03/env.hpp
+++ b/code/compiler/03/env.hpp
@ -0,0 +1,16 @@
+#pragma once
+#include <map>
+#include "type.hpp"
+
+struct type_env {
+    std::map<std::string, type_ptr> names;
+    type_env const* parent = nullptr;
+
+    type_env(type_env const* p)
+        : parent(p) {}
+    type_env() : type_env(nullptr) {}
+
+    type_ptr lookup(const std::string& name) const;
+    void bind(const std::string& name, type_ptr t);
+    type_env scope() const;
+};
--- a/code/compiler/03/main.cpp
+++ b/code/compiler/03/main.cpp
@ -0,0 +1,39 @@
+#include "ast.hpp"
+#include "parser.hpp"
+#include "type.hpp"
+
+void yy::parser::error(const std::string& msg) {
+    std::cout << "An error occured: " << msg << std::endl;
+}
+
+extern std::vector<definition_ptr> program;
+
+void typecheck_program(const std::vector<definition_ptr>& prog) {
+    type_mgr mgr;
+    type_env env;
+
+    type_ptr int_type = type_ptr(new type_base("Int")); 
+    type_ptr binop_type = type_ptr(new type_arr(
+                int_type,
+                type_ptr(new type_arr(int_type, int_type))));
+
+    env.bind("+", binop_type);
+    env.bind("-", binop_type);
+    env.bind("*", binop_type);
+    env.bind("/", binop_type);
+
+    for(auto& def : prog) {
+        def->typecheck_first(mgr, env);
+    }
+
+    for(auto& def : prog) {
+        def->typecheck_second(mgr, env);
+    }
+}
+
+int main() {
+    yy::parser parser;
+    parser.parse();
+    typecheck_program(program);
+    std::cout << program.size() << std::endl;
+}
--- a/code/compiler/03/parser.y
+++ b/code/compiler/03/parser.y
@ -0,0 +1,140 @@
+%{
+#include <string>
+#include <iostream>
+#include "ast.hpp"
+#include "parser.hpp"
+
+std::vector<definition_ptr> program;
+extern yy::parser::symbol_type yylex();
+
+%}
+
+%token PLUS
+%token TIMES
+%token MINUS
+%token DIVIDE
+%token <int> INT
+%token DEFN
+%token DATA
+%token CASE
+%token OF
+%token OCURLY
+%token CCURLY
+%token OPAREN
+%token CPAREN
+%token COMMA
+%token ARROW
+%token EQUAL
+%token <std::string> LID
+%token <std::string> UID
+
+%language "c++"
+%define api.value.type variant
+%define api.token.constructor
+
+%type <std::vector<std::string>> lowercaseParams uppercaseParams
+%type <std::vector<definition_ptr>> program definitions
+%type <std::vector<branch_ptr>> branches
+%type <std::vector<constructor_ptr>> constructors
+%type <ast_ptr> aAdd aMul case app appBase
+%type <definition_ptr> definition defn data 
+%type <branch_ptr> branch
+%type <pattern_ptr> pattern
+%type <constructor_ptr> constructor
+
+%start program
+
+%%
+
+program
+    : definitions { program = std::move($1); }
+    ;
+
+definitions
+    : definitions definition { $$ = std::move($1); $$.push_back(std::move($2)); }
+    | definition { $$ = std::vector<definition_ptr>(); $$.push_back(std::move($1)); }
+    ;
+
+definition
+    : defn { $$ = std::move($1); }
+    | data { $$ = std::move($1); }
+    ;
+
+defn
+    : DEFN LID lowercaseParams EQUAL OCURLY aAdd CCURLY
+        { $$ = definition_ptr(
+            new definition_defn(std::move($2), std::move($3), std::move($6))); }
+    ;
+
+lowercaseParams
+    : %empty { $$ = std::vector<std::string>(); }
+    | lowercaseParams LID { $$ = std::move($1); $$.push_back(std::move($2)); }
+    ;
+
+uppercaseParams
+    : %empty { $$ = std::vector<std::string>(); }
+    | uppercaseParams UID { $$ = std::move($1); $$.push_back(std::move($2)); }
+    ;
+
+aAdd
+    : aAdd PLUS aMul { $$ = ast_ptr(new ast_binop(PLUS, std::move($1), std::move($3))); }
+    | aAdd MINUS aMul { $$ = ast_ptr(new ast_binop(MINUS, std::move($1), std::move($3))); }
+    | aMul { $$ = std::move($1); }
+    ;
+
+aMul
+    : aMul TIMES app { $$ = ast_ptr(new ast_binop(TIMES, std::move($1), std::move($3))); }
+    | aMul DIVIDE app { $$ = ast_ptr(new ast_binop(DIVIDE, std::move($1), std::move($3))); }
+    | app { $$ = std::move($1); }
+    ;
+
+app
+    : app appBase { $$ = ast_ptr(new ast_app(std::move($1), std::move($2))); }
+    | appBase { $$ = std::move($1); }
+    ;
+
+appBase
+    : INT { $$ = ast_ptr(new ast_int($1)); }
+    | LID { $$ = ast_ptr(new ast_lid(std::move($1))); }
+    | UID { $$ = ast_ptr(new ast_uid(std::move($1))); }
+    | OPAREN aAdd CPAREN { $$ = std::move($2); }
+    | case { $$ = std::move($1); }
+    ;
+
+case
+    : CASE aAdd OF OCURLY branches CCURLY 
+        { $$ = ast_ptr(new ast_case(std::move($2), std::move($5))); }
+    ;
+
+branches
+    : branches branch { $$ = std::move($1); $1.push_back(std::move($2)); }
+    | branch { $$ = std::vector<branch_ptr>(); $$.push_back(std::move($1));}
+    ;
+
+branch
+    : pattern ARROW OCURLY aAdd CCURLY
+        { $$ = branch_ptr(new branch(std::move($1), std::move($4))); }
+    ;
+
+pattern
+    : LID { $$ = pattern_ptr(new pattern_var(std::move($1))); }
+    | UID lowercaseParams
+        { $$ = pattern_ptr(new pattern_constr(std::move($1), std::move($2))); }
+    ;
+
+data
+    : DATA UID EQUAL OCURLY constructors CCURLY
+        { $$ = definition_ptr(new definition_data(std::move($2), std::move($5))); }
+    ;
+
+constructors
+    : constructors COMMA constructor { $$ = std::move($1); $$.push_back(std::move($3)); }
+    | constructor
+        { $$ = std::vector<constructor_ptr>(); $$.push_back(std::move($1)); }
+    ;
+
+constructor
+    : UID uppercaseParams
+        { $$ = constructor_ptr(new constructor(std::move($1), std::move($2))); }
+    ;
+
--- a/code/compiler/03/scanner.l
+++ b/code/compiler/03/scanner.l
@ -0,0 +1,34 @@
+%option noyywrap
+
+%{
+#include <iostream>
+#include "ast.hpp"
+#include "parser.hpp"
+
+#define YY_DECL yy::parser::symbol_type yylex()
+
+%}
+
+%%
+
+[ \n]+ {}
+\+ { return yy::parser::make_PLUS(); }
+\* { return yy::parser::make_TIMES(); }
+- { return yy::parser::make_MINUS(); }
+\/ { return yy::parser::make_DIVIDE(); }
+[0-9]+ { return yy::parser::make_INT(atoi(yytext)); }
+defn { return yy::parser::make_DEFN(); }
+data { return yy::parser::make_DATA(); }
+case { return yy::parser::make_CASE(); }
+of { return yy::parser::make_OF(); }
+\{ { return yy::parser::make_OCURLY(); }
+\} { return yy::parser::make_CCURLY(); }
+\( { return yy::parser::make_OPAREN(); }
+\) { return yy::parser::make_CPAREN(); }
+,  { return yy::parser::make_COMMA(); }
+-> { return yy::parser::make_ARROW(); }
+= { return yy::parser::make_EQUAL(); }
+[a-z][a-zA-Z]* { return yy::parser::make_LID(std::string(yytext)); }
+[A-Z][a-zA-Z]* { return yy::parser::make_UID(std::string(yytext)); }
+
+%%
--- a/code/compiler/03/type.cpp
+++ b/code/compiler/03/type.cpp
@ -0,0 +1,78 @@
+#include "type.hpp"
+#include <sstream>
+#include <algorithm>
+
+std::string type_mgr::new_type_name() {
+    int temp = last_id++;
+    std::string str = "";
+
+    while(temp != -1) {
+        str += (char) ('a' + (temp % 26));
+        temp = temp / 26 - 1;
+    }
+
+    std::reverse(str.begin(), str.end());
+    return str;
+}
+
+type_ptr type_mgr::new_type() {
+    return type_ptr(new type_var(new_type_name()));
+}
+
+type_ptr type_mgr::new_arrow_type() {
+    return type_ptr(new type_arr(new_type(), new_type()));
+}
+
+type_ptr type_mgr::resolve(type_ptr t, type_var*& var) {
+    type_var* cast;
+
+    var = nullptr;
+    while((cast = dynamic_cast<type_var*>(t.get()))) {
+        auto it = types.find(cast->name);
+
+        if(it == types.end()) {
+            var = cast;
+            break;
+        }
+        t = it->second;
+    }
+
+    return t;
+}
+
+void type_mgr::unify(type_ptr l, type_ptr r) {
+    type_var* lvar;
+    type_var* rvar;
+    type_arr* larr;
+    type_arr* rarr;
+    type_base* lid;
+    type_base* rid;
+
+    l = resolve(l, lvar);
+    r = resolve(r, rvar);
+
+    if(lvar) {
+        bind(lvar->name, r);
+        return;
+    } else if(rvar) {
+        bind(rvar->name, l);
+        return;
+    } else if((larr = dynamic_cast<type_arr*>(l.get())) &&
+            (rarr = dynamic_cast<type_arr*>(r.get()))) {
+        unify(larr->left, rarr->left);
+        unify(larr->right, rarr->right);
+        return;
+    } else if((lid = dynamic_cast<type_base*>(l.get())) &&
+            (rid = dynamic_cast<type_base*>(r.get()))) {
+        if(lid->name == rid->name) return;
+    }
+
+    throw 0;
+}
+
+void type_mgr::bind(const std::string& s, type_ptr t) {
+    type_var* other = dynamic_cast<type_var*>(t.get());
+    
+    if(other && other->name == s) return;
+    types[s] = t;
+}
--- a/code/compiler/03/type.hpp
+++ b/code/compiler/03/type.hpp
@ -0,0 +1,44 @@
+#pragma once
+#include <memory>
+#include <map>
+
+struct type {
+    virtual ~type() = default;
+};
+
+using type_ptr = std::shared_ptr<type>;
+
+struct type_var : public type {
+    std::string name;
+
+    type_var(std::string n)
+        : name(std::move(n)) {}
+};
+
+struct type_base : public type {
+    std::string name;
+
+    type_base(std::string n) 
+        : name(std::move(n)) {}
+};
+
+struct type_arr : public type {
+    type_ptr left;
+    type_ptr right;
+
+    type_arr(type_ptr l, type_ptr r)
+        : left(std::move(l)), right(std::move(r)) {}
+};
+
+struct type_mgr {
+    int last_id = 0;
+    std::map<std::string, type_ptr> types;
+
+    std::string new_type_name();
+    type_ptr new_type();
+    type_ptr new_arrow_type();
+
+    void unify(type_ptr l, type_ptr r);
+    type_ptr resolve(type_ptr t, type_var*& var);
+    void bind(const std::string& s, type_ptr t);
+};
--- a/code/compiler/03/works1.txt
+++ b/code/compiler/03/works1.txt
@ -0,0 +1,2 @@
+defn main = { plus 320 6 }
+defn plus x y = { x + y }
--- a/code/compiler/03/works2.txt
+++ b/code/compiler/03/works2.txt
@ -0,0 +1,3 @@
+defn add x y = { x + y }
+defn double x = { add x x }
+defn main = { double 163 }
--- a/code/compiler/03/works3.txt
+++ b/code/compiler/03/works3.txt
@ -0,0 +1,7 @@
+data List = { Nil, Cons Int List }
+defn length l = {
+    case l of {
+        Nil -> { 0 }
+        Cons x xs -> { 1 + length xs }
+    }
+}
--- a/code/compiler/04/CMakeLists.txt
+++ b/code/compiler/04/CMakeLists.txt
@ -0,0 +1,25 @@
+cmake_minimum_required(VERSION 3.1)
+project(compiler)
+
+find_package(BISON)
+find_package(FLEX)
+bison_target(parser
+    ${CMAKE_CURRENT_SOURCE_DIR}/parser.y
+    ${CMAKE_CURRENT_BINARY_DIR}/parser.cpp
+    COMPILE_FLAGS "-d")
+flex_target(scanner
+    ${CMAKE_CURRENT_SOURCE_DIR}/scanner.l
+    ${CMAKE_CURRENT_BINARY_DIR}/scanner.cpp)
+add_flex_bison_dependency(scanner parser)
+
+add_executable(compiler
+    ast.cpp ast.hpp definition.cpp
+    env.cpp env.hpp
+    type.cpp type.hpp
+    error.cpp error.hpp
+    ${BISON_parser_OUTPUTS}
+    ${FLEX_scanner_OUTPUTS}
+    main.cpp
+)
+target_include_directories(compiler PUBLIC ${CMAKE_CURRENT_SOURCE_DIR})
+target_include_directories(compiler PUBLIC ${CMAKE_CURRENT_BINARY_DIR})
--- a/code/compiler/04/ast.cpp
+++ b/code/compiler/04/ast.cpp
@ -0,0 +1,145 @@
+#include "ast.hpp"
+#include <ostream>
+#include "error.hpp"
+
+std::string op_name(binop op) {
+    switch(op) {
+        case PLUS: return "+";
+        case MINUS: return "-";
+        case TIMES: return "*";
+        case DIVIDE: return "/";
+    }
+    return "??";
+}
+
+void print_indent(int n, std::ostream& to) {
+    while(n--) to << "  ";
+}
+
+void ast_int::print(int indent, std::ostream& to) const {
+    print_indent(indent, to);
+    to << "INT: " << value << std::endl;
+}
+
+type_ptr ast_int::typecheck(type_mgr& mgr, const type_env& env) const {
+    return type_ptr(new type_base("Int"));
+}
+
+void ast_lid::print(int indent, std::ostream& to) const {
+    print_indent(indent, to);
+    to << "LID: " << id << std::endl;
+}
+
+type_ptr ast_lid::typecheck(type_mgr& mgr, const type_env& env) const {
+    return env.lookup(id);
+}
+
+void ast_uid::print(int indent, std::ostream& to) const {
+    print_indent(indent, to);
+    to << "UID: " << id << std::endl;
+}
+
+type_ptr ast_uid::typecheck(type_mgr& mgr, const type_env& env) const {
+    return env.lookup(id);
+}
+
+void ast_binop::print(int indent, std::ostream& to) const {
+    print_indent(indent, to);
+    to << "BINOP: " << op_name(op) << std::endl;
+    left->print(indent + 1, to);
+    right->print(indent + 1, to);
+}
+
+type_ptr ast_binop::typecheck(type_mgr& mgr, const type_env& env) const {
+    type_ptr ltype = left->typecheck(mgr, env);
+    type_ptr rtype = right->typecheck(mgr, env);
+    type_ptr ftype = env.lookup(op_name(op));
+    if(!ftype) throw type_error(std::string("unknown binary operator ") + op_name(op));
+
+    type_ptr return_type = mgr.new_type();
+    type_ptr arrow_one = type_ptr(new type_arr(rtype, return_type));
+    type_ptr arrow_two = type_ptr(new type_arr(ltype, arrow_one));
+
+    mgr.unify(arrow_two, ftype);
+    return return_type;
+}
+
+void ast_app::print(int indent, std::ostream& to) const {
+    print_indent(indent, to);
+    to << "APP:" << std::endl;
+    left->print(indent + 1, to);
+    right->print(indent + 1, to);
+}
+
+type_ptr ast_app::typecheck(type_mgr& mgr, const type_env& env) const {
+    type_ptr ltype = left->typecheck(mgr, env);
+    type_ptr rtype = right->typecheck(mgr, env);
+
+    type_ptr return_type = mgr.new_type();
+    type_ptr arrow = type_ptr(new type_arr(rtype, return_type));
+    mgr.unify(arrow, ltype);
+    return return_type;
+}
+
+void ast_case::print(int indent, std::ostream& to) const {
+    print_indent(indent, to);
+    to << "CASE: " << std::endl;
+    for(auto& branch : branches) {
+        print_indent(indent + 1, to);
+        branch->pat->print(to);
+        to << std::endl;
+        branch->expr->print(indent + 2, to);
+    }
+}
+
+type_ptr ast_case::typecheck(type_mgr& mgr, const type_env& env) const {
+    type_var* var;
+    type_ptr case_type = mgr.resolve(of->typecheck(mgr, env), var);
+    type_ptr branch_type = mgr.new_type();
+
+    for(auto& branch : branches) {
+        type_env new_env = env.scope();
+        branch->pat->match(case_type, mgr, new_env);
+        type_ptr curr_branch_type = branch->expr->typecheck(mgr, new_env);
+        mgr.unify(branch_type, curr_branch_type);
+    }
+
+    case_type = mgr.resolve(case_type, var);
+    if(!dynamic_cast<type_base*>(case_type.get())) {
+        throw type_error("attempting case analysis of non-data type");
+    }
+
+    return branch_type;
+}
+
+void pattern_var::print(std::ostream& to) const {
+    to << var;
+}
+
+void pattern_var::match(type_ptr t, type_mgr& mgr, type_env& env) const {
+    env.bind(var, t);
+}
+
+void pattern_constr::print(std::ostream& to) const {
+    to << constr;
+    for(auto& param : params) {
+        to << " " << param;
+    }
+}
+
+void pattern_constr::match(type_ptr t, type_mgr& mgr, type_env& env) const {
+    type_ptr constructor_type = env.lookup(constr);
+    if(!constructor_type) {
+        throw type_error(std::string("pattern using unknown constructor ") + constr);
+    }
+
+    for(int i = 0; i < params.size(); i++) {
+        type_arr* arr = dynamic_cast<type_arr*>(constructor_type.get());
+        if(!arr) throw type_error("too many parameters in constructor pattern");
+
+        env.bind(params[i], arr->left);
+        constructor_type = arr->right;
+    }
+
+    mgr.unify(t, constructor_type);
+}
--- a/code/compiler/04/ast.hpp
+++ b/code/compiler/04/ast.hpp
@ -0,0 +1,172 @@
+#pragma once
+#include <memory>
+#include <vector>
+#include "type.hpp"
+#include "env.hpp"
+
+struct ast {
+    virtual ~ast() = default;
+
+    virtual void print(int indent, std::ostream& to) const = 0;
+    virtual type_ptr typecheck(type_mgr& mgr, const type_env& env) const = 0;
+};
+
+using ast_ptr = std::unique_ptr<ast>;
+
+struct pattern {
+    virtual ~pattern() = default;
+
+    virtual void print(std::ostream& to) const = 0;
+    virtual void match(type_ptr t, type_mgr& mgr, type_env& env) const = 0;
+};
+
+using pattern_ptr = std::unique_ptr<pattern>;
+
+struct branch {
+    pattern_ptr pat;
+    ast_ptr expr;
+
+    branch(pattern_ptr p, ast_ptr a)
+        : pat(std::move(p)), expr(std::move(a)) {}
+};
+
+using branch_ptr = std::unique_ptr<branch>;
+
+struct constructor {
+    std::string name;
+    std::vector<std::string> types;
+
+    constructor(std::string n, std::vector<std::string> ts)
+        : name(std::move(n)), types(std::move(ts)) {}
+};
+
+using constructor_ptr = std::unique_ptr<constructor>;
+
+struct definition {
+    virtual ~definition() = default;
+    
+    virtual void typecheck_first(type_mgr& mgr, type_env& env) = 0;
+    virtual void typecheck_second(type_mgr& mgr, const type_env& env) const = 0;
+};
+
+using definition_ptr = std::unique_ptr<definition>;
+
+enum binop {
+    PLUS,
+    MINUS,
+    TIMES,
+    DIVIDE
+};
+
+struct ast_int : public ast {
+    int value;
+
+    explicit ast_int(int v)
+        : value(v) {}
+
+    void print(int indent, std::ostream& to) const;
+    type_ptr typecheck(type_mgr& mgr, const type_env& env) const;
+};
+
+struct ast_lid : public ast {
+    std::string id;
+
+    explicit ast_lid(std::string i)
+        : id(std::move(i)) {}
+
+    void print(int indent, std::ostream& to) const;
+    type_ptr typecheck(type_mgr& mgr, const type_env& env) const;
+};
+
+struct ast_uid : public ast {
+    std::string id;
+
+    explicit ast_uid(std::string i)
+        : id(std::move(i)) {}
+
+    void print(int indent, std::ostream& to) const;
+    type_ptr typecheck(type_mgr& mgr, const type_env& env) const;
+};
+
+struct ast_binop : public ast {
+    binop op;  
+    ast_ptr left;
+    ast_ptr right;
+
+    ast_binop(binop o, ast_ptr l, ast_ptr r)
+        : op(o), left(std::move(l)), right(std::move(r)) {}
+
+    void print(int indent, std::ostream& to) const;
+    type_ptr typecheck(type_mgr& mgr, const type_env& env) const;
+};
+
+struct ast_app : public ast {
+    ast_ptr left;
+    ast_ptr right;
+
+    ast_app(ast_ptr l, ast_ptr r)
+        : left(std::move(l)), right(std::move(r)) {}
+
+    void print(int indent, std::ostream& to) const;
+    type_ptr typecheck(type_mgr& mgr, const type_env& env) const;
+};
+
+struct ast_case : public ast {
+    ast_ptr of;
+    std::vector<branch_ptr> branches;
+
+    ast_case(ast_ptr o, std::vector<branch_ptr> b)
+        : of(std::move(o)), branches(std::move(b)) {}
+
+    void print(int indent, std::ostream& to) const;
+    type_ptr typecheck(type_mgr& mgr, const type_env& env) const;
+};
+
+struct pattern_var : public pattern {
+    std::string var;
+
+    pattern_var(std::string v)
+        : var(std::move(v)) {}
+
+    void print(std::ostream &to) const;
+    void match(type_ptr t, type_mgr& mgr, type_env& env) const;
+};
+
+struct pattern_constr : public pattern {
+    std::string constr;
+    std::vector<std::string> params;
+
+    pattern_constr(std::string c, std::vector<std::string> p)
+        : constr(std::move(c)), params(std::move(p)) {}
+
+    void print(std::ostream &to) const;
+    void match(type_ptr t, type_mgr&, type_env& env) const;
+};
+
+struct definition_defn : public definition {
+    std::string name;
+    std::vector<std::string> params;
+    ast_ptr body;
+
+    type_ptr return_type;
+    std::vector<type_ptr> param_types;
+
+    definition_defn(std::string n, std::vector<std::string> p, ast_ptr b)
+        : name(std::move(n)), params(std::move(p)), body(std::move(b)) {
+
+    }
+
+    void typecheck_first(type_mgr& mgr, type_env& env);
+    void typecheck_second(type_mgr& mgr, const type_env& env) const;
+};
+
+struct definition_data : public definition {
+    std::string name;
+    std::vector<constructor_ptr> constructors;
+
+    definition_data(std::string n, std::vector<constructor_ptr> cs)
+        : name(std::move(n)), constructors(std::move(cs)) {}
+
+    void typecheck_first(type_mgr& mgr, type_env& env);
+    void typecheck_second(type_mgr& mgr, const type_env& env) const;
+};
--- a/code/compiler/04/definition.cpp
+++ b/code/compiler/04/definition.cpp
@ -0,0 +1,48 @@
+#include "ast.hpp"
+
+void definition_defn::typecheck_first(type_mgr& mgr, type_env& env) {
+    return_type = mgr.new_type();
+    type_ptr full_type = return_type;
+
+    for(auto it = params.rbegin(); it != params.rend(); it++) {
+        type_ptr param_type = mgr.new_type();
+        full_type = type_ptr(new type_arr(param_type, full_type));
+        param_types.push_back(param_type);
+    }
+
+    env.bind(name, full_type);
+}
+
+void definition_defn::typecheck_second(type_mgr& mgr, const type_env& env) const {
+    type_env new_env = env.scope();
+    auto param_it = params.begin();
+    auto type_it = param_types.rbegin();
+
+    while(param_it != params.end() && type_it != param_types.rend()) {
+        new_env.bind(*param_it, *type_it);
+        param_it++;
+        type_it++;
+    }
+
+    type_ptr body_type = body->typecheck(mgr, new_env);
+    mgr.unify(return_type, body_type);
+}
+
+void definition_data::typecheck_first(type_mgr& mgr, type_env& env) {
+    type_ptr return_type = type_ptr(new type_base(name));
+
+    for(auto& constructor : constructors) {
+        type_ptr full_type = return_type;
+
+        for(auto it = constructor->types.rbegin(); it != constructor->types.rend(); it++) {
+            type_ptr type = type_ptr(new type_base(*it));
+            full_type = type_ptr(new type_arr(type, full_type));
+        }
+
+        env.bind(constructor->name, full_type);
+    }
+}
+
+void definition_data::typecheck_second(type_mgr& mgr, const type_env& env) const {
+    // Nothing
+}
--- a/code/compiler/04/env.cpp
+++ b/code/compiler/04/env.cpp
@ -0,0 +1,16 @@
+#include "env.hpp"
+
+type_ptr type_env::lookup(const std::string& name) const {
+    auto it = names.find(name);
+    if(it != names.end()) return it->second;
+    if(parent) return parent->lookup(name);
+    return nullptr;
+}
+
+void type_env::bind(const std::string& name, type_ptr t) {
+    names[name] = t;
+}
+
+type_env type_env::scope() const {
+    return type_env(this);
+}
--- a/code/compiler/04/env.hpp
+++ b/code/compiler/04/env.hpp
@ -0,0 +1,16 @@
+#pragma once
+#include <map>
+#include "type.hpp"
+
+struct type_env {
+    std::map<std::string, type_ptr> names;
+    type_env const* parent = nullptr;
+
+    type_env(type_env const* p)
+        : parent(p) {}
+    type_env() : type_env(nullptr) {}
+
+    type_ptr lookup(const std::string& name) const;
+    void bind(const std::string& name, type_ptr t);
+    type_env scope() const;
+};
--- a/code/compiler/04/error.cpp
+++ b/code/compiler/04/error.cpp
@ -0,0 +1,5 @@
+#include "error.hpp"
+
+const char* type_error::what() const noexcept {
+    return "an error occured while checking the types of the program";
+}
--- a/code/compiler/04/error.hpp
+++ b/code/compiler/04/error.hpp
@ -0,0 +1,21 @@
+#pragma once
+#include <exception>
+#include "type.hpp"
+
+struct type_error : std::exception {
+    std::string description;
+
+    type_error(std::string d)
+        : description(std::move(d)) {}
+
+    const char* what() const noexcept override;
+};
+
+struct unification_error : public type_error {
+    type_ptr left;
+    type_ptr right;
+
+    unification_error(type_ptr l, type_ptr r)
+        : left(std::move(l)), right(std::move(r)), 
+            type_error("failed to unify types") {}
+};
--- a/code/compiler/04/examples/bad1.txt
+++ b/code/compiler/04/examples/bad1.txt
@ -0,0 +1,2 @@
+data Bool = { True, False }
+defn main = { 3 + True }
--- a/code/compiler/04/examples/bad2.txt
+++ b/code/compiler/04/examples/bad2.txt
@ -0,0 +1 @@
+defn main = { 1 2 3 4 5 }
--- a/code/compiler/04/examples/works1.txt
+++ b/code/compiler/04/examples/works1.txt
@ -0,0 +1,2 @@
+defn main = { plus 320 6 }
+defn plus x y = { x + y }
--- a/code/compiler/04/examples/works2.txt
+++ b/code/compiler/04/examples/works2.txt
@ -0,0 +1,3 @@
+defn add x y = { x + y }
+defn double x = { add x x }
+defn main = { double 163 }
--- a/code/compiler/04/examples/works3.txt
+++ b/code/compiler/04/examples/works3.txt
@ -0,0 +1,7 @@
+data List = { Nil, Cons Int List }
+defn length l = {
+    case l of {
+        Nil -> { 0 }
+        Cons x xs -> { 1 + length xs }
+    }
+}
--- a/code/compiler/04/main.cpp
+++ b/code/compiler/04/main.cpp
@ -0,0 +1,70 @@
+#include "ast.hpp"
+#include <iostream>
+#include "parser.hpp"
+#include "error.hpp"
+#include "type.hpp"
+
+void yy::parser::error(const std::string& msg) {
+    std::cout << "An error occured: " << msg << std::endl;
+}
+
+extern std::vector<definition_ptr> program;
+
+void typecheck_program(
+        const std::vector<definition_ptr>& prog,
+        type_mgr& mgr, type_env& env) {
+    type_ptr int_type = type_ptr(new type_base("Int")); 
+    type_ptr binop_type = type_ptr(new type_arr(
+                int_type,
+                type_ptr(new type_arr(int_type, int_type))));
+
+    env.bind("+", binop_type);
+    env.bind("-", binop_type);
+    env.bind("*", binop_type);
+    env.bind("/", binop_type);
+
+    for(auto& def : prog) {
+        def->typecheck_first(mgr, env);
+    }
+
+    for(auto& def : prog) {
+        def->typecheck_second(mgr, env);
+    }
+
+    for(auto& pair : env.names) {
+        std::cout << pair.first << ": ";
+        pair.second->print(mgr, std::cout);
+        std::cout << std::endl;
+    }
+}
+
+int main() {
+    yy::parser parser;
+    type_mgr mgr;
+    type_env env;
+
+    parser.parse();
+    for(auto& definition : program) {
+        definition_defn* def = dynamic_cast<definition_defn*>(definition.get());
+        if(!def) continue;
+
+        std::cout << def->name;
+        for(auto& param : def->params) std::cout << " " << param;
+        std::cout << ":" << std::endl;
+
+        def->body->print(1, std::cout);
+    }
+    try {
+        typecheck_program(program, mgr, env);
+    } catch(unification_error& err) {
+        std::cout << "failed to unify types: " << std::endl;
+        std::cout << "  (1) \033[34m";
+        err.left->print(mgr, std::cout);
+        std::cout << "\033[0m" << std::endl;
+        std::cout << "  (2) \033[32m";
+        err.right->print(mgr, std::cout);
+        std::cout << "\033[0m" << std::endl;
+    } catch(type_error& err) {
+        std::cout << "failed to type check program: " << err.description << std::endl;
+    }
+}
--- a/code/compiler/04/parser.y
+++ b/code/compiler/04/parser.y
@ -0,0 +1,140 @@
+%{
+#include <string>
+#include <iostream>
+#include "ast.hpp"
+#include "parser.hpp"
+
+std::vector<definition_ptr> program;
+extern yy::parser::symbol_type yylex();
+
+%}
+
+%token PLUS
+%token TIMES
+%token MINUS
+%token DIVIDE
+%token <int> INT
+%token DEFN
+%token DATA
+%token CASE
+%token OF
+%token OCURLY
+%token CCURLY
+%token OPAREN
+%token CPAREN
+%token COMMA
+%token ARROW
+%token EQUAL
+%token <std::string> LID
+%token <std::string> UID
+
+%language "c++"
+%define api.value.type variant
+%define api.token.constructor
+
+%type <std::vector<std::string>> lowercaseParams uppercaseParams
+%type <std::vector<definition_ptr>> program definitions
+%type <std::vector<branch_ptr>> branches
+%type <std::vector<constructor_ptr>> constructors
+%type <ast_ptr> aAdd aMul case app appBase
+%type <definition_ptr> definition defn data 
+%type <branch_ptr> branch
+%type <pattern_ptr> pattern
+%type <constructor_ptr> constructor
+
+%start program
+
+%%
+
+program
+    : definitions { program = std::move($1); }
+    ;
+
+definitions
+    : definitions definition { $$ = std::move($1); $$.push_back(std::move($2)); }
+    | definition { $$ = std::vector<definition_ptr>(); $$.push_back(std::move($1)); }
+    ;
+
+definition
+    : defn { $$ = std::move($1); }
+    | data { $$ = std::move($1); }
+    ;
+
+defn
+    : DEFN LID lowercaseParams EQUAL OCURLY aAdd CCURLY
+        { $$ = definition_ptr(
+            new definition_defn(std::move($2), std::move($3), std::move($6))); }
+    ;
+
+lowercaseParams
+    : %empty { $$ = std::vector<std::string>(); }
+    | lowercaseParams LID { $$ = std::move($1); $$.push_back(std::move($2)); }
+    ;
+
+uppercaseParams
+    : %empty { $$ = std::vector<std::string>(); }
+    | uppercaseParams UID { $$ = std::move($1); $$.push_back(std::move($2)); }
+    ;
+
+aAdd
+    : aAdd PLUS aMul { $$ = ast_ptr(new ast_binop(PLUS, std::move($1), std::move($3))); }
+    | aAdd MINUS aMul { $$ = ast_ptr(new ast_binop(MINUS, std::move($1), std::move($3))); }
+    | aMul { $$ = std::move($1); }
+    ;
+
+aMul
+    : aMul TIMES app { $$ = ast_ptr(new ast_binop(TIMES, std::move($1), std::move($3))); }
+    | aMul DIVIDE app { $$ = ast_ptr(new ast_binop(DIVIDE, std::move($1), std::move($3))); }
+    | app { $$ = std::move($1); }
+    ;
+
+app
+    : app appBase { $$ = ast_ptr(new ast_app(std::move($1), std::move($2))); }
+    | appBase { $$ = std::move($1); }
+    ;
+
+appBase
+    : INT { $$ = ast_ptr(new ast_int($1)); }
+    | LID { $$ = ast_ptr(new ast_lid(std::move($1))); }
+    | UID { $$ = ast_ptr(new ast_uid(std::move($1))); }
+    | OPAREN aAdd CPAREN { $$ = std::move($2); }
+    | case { $$ = std::move($1); }
+    ;
+
+case
+    : CASE aAdd OF OCURLY branches CCURLY 
+        { $$ = ast_ptr(new ast_case(std::move($2), std::move($5))); }
+    ;
+
+branches
+    : branches branch { $$ = std::move($1); $$.push_back(std::move($2)); }
+    | branch { $$ = std::vector<branch_ptr>(); $$.push_back(std::move($1));}
+    ;
+
+branch
+    : pattern ARROW OCURLY aAdd CCURLY
+        { $$ = branch_ptr(new branch(std::move($1), std::move($4))); }
+    ;
+
+pattern
+    : LID { $$ = pattern_ptr(new pattern_var(std::move($1))); }
+    | UID lowercaseParams
+        { $$ = pattern_ptr(new pattern_constr(std::move($1), std::move($2))); }
+    ;
+
+data
+    : DATA UID EQUAL OCURLY constructors CCURLY
+        { $$ = definition_ptr(new definition_data(std::move($2), std::move($5))); }
+    ;
+
+constructors
+    : constructors COMMA constructor { $$ = std::move($1); $$.push_back(std::move($3)); }
+    | constructor
+        { $$ = std::vector<constructor_ptr>(); $$.push_back(std::move($1)); }
+    ;
+
+constructor
+    : UID uppercaseParams
+        { $$ = constructor_ptr(new constructor(std::move($1), std::move($2))); }
+    ;
+
--- a/code/compiler/04/scanner.l
+++ b/code/compiler/04/scanner.l
@ -0,0 +1,34 @@
+%option noyywrap
+
+%{
+#include <iostream>
+#include "ast.hpp"
+#include "parser.hpp"
+
+#define YY_DECL yy::parser::symbol_type yylex()
+
+%}
+
+%%
+
+[ \n]+ {}
+\+ { return yy::parser::make_PLUS(); }
+\* { return yy::parser::make_TIMES(); }
+- { return yy::parser::make_MINUS(); }
+\/ { return yy::parser::make_DIVIDE(); }
+[0-9]+ { return yy::parser::make_INT(atoi(yytext)); }
+defn { return yy::parser::make_DEFN(); }
+data { return yy::parser::make_DATA(); }
+case { return yy::parser::make_CASE(); }
+of { return yy::parser::make_OF(); }
+\{ { return yy::parser::make_OCURLY(); }
+\} { return yy::parser::make_CCURLY(); }
+\( { return yy::parser::make_OPAREN(); }
+\) { return yy::parser::make_CPAREN(); }
+,  { return yy::parser::make_COMMA(); }
+-> { return yy::parser::make_ARROW(); }
+= { return yy::parser::make_EQUAL(); }
+[a-z][a-zA-Z]* { return yy::parser::make_LID(std::string(yytext)); }
+[A-Z][a-zA-Z]* { return yy::parser::make_UID(std::string(yytext)); }
+
+%%
--- a/code/compiler/04/type.cpp
+++ b/code/compiler/04/type.cpp
@ -0,0 +1,99 @@
+#include "type.hpp"
+#include <sstream>
+#include <algorithm>
+#include "error.hpp"
+
+void type_var::print(const type_mgr& mgr, std::ostream& to) const {
+    auto it = mgr.types.find(name);
+    if(it != mgr.types.end()) {
+        it->second->print(mgr, to);
+    } else {
+        to << name;
+    }
+}
+
+void type_base::print(const type_mgr& mgr, std::ostream& to) const {
+    to << name;
+}
+
+void type_arr::print(const type_mgr& mgr, std::ostream& to) const {
+    left->print(mgr, to);
+    to << " -> (";
+    right->print(mgr, to);
+    to << ")";
+}
+
+std::string type_mgr::new_type_name() {
+    int temp = last_id++;
+    std::string str = "";
+
+    while(temp != -1) {
+        str += (char) ('a' + (temp % 26));
+        temp = temp / 26 - 1;
+    }
+
+    std::reverse(str.begin(), str.end());
+    return str;
+}
+
+type_ptr type_mgr::new_type() {
+    return type_ptr(new type_var(new_type_name()));
+}
+
+type_ptr type_mgr::new_arrow_type() {
+    return type_ptr(new type_arr(new_type(), new_type()));
+}
+
+type_ptr type_mgr::resolve(type_ptr t, type_var*& var) {
+    type_var* cast;
+
+    var = nullptr;
+    while((cast = dynamic_cast<type_var*>(t.get()))) {
+        auto it = types.find(cast->name);
+
+        if(it == types.end()) {
+            var = cast;
+            break;
+        }
+        t = it->second;
+    }
+
+    return t;
+}
+
+void type_mgr::unify(type_ptr l, type_ptr r) {
+    type_var* lvar;
+    type_var* rvar;
+    type_arr* larr;
+    type_arr* rarr;
+    type_base* lid;
+    type_base* rid;
+
+    l = resolve(l, lvar);
+    r = resolve(r, rvar);
+
+    if(lvar) {
+        bind(lvar->name, r);
+        return;
+    } else if(rvar) {
+        bind(rvar->name, l);
+        return;
+    } else if((larr = dynamic_cast<type_arr*>(l.get())) &&
+            (rarr = dynamic_cast<type_arr*>(r.get()))) {
+        unify(larr->left, rarr->left);
+        unify(larr->right, rarr->right);
+        return;
+    } else if((lid = dynamic_cast<type_base*>(l.get())) &&
+            (rid = dynamic_cast<type_base*>(r.get()))) {
+        if(lid->name == rid->name) return;
+    }
+
+    throw unification_error(l, r);
+}
+
+void type_mgr::bind(const std::string& s, type_ptr t) {
+    type_var* other = dynamic_cast<type_var*>(t.get());
+    
+    if(other && other->name == s) return;
+    types[s] = t;
+}
--- a/code/compiler/04/type.hpp
+++ b/code/compiler/04/type.hpp
@ -0,0 +1,54 @@
+#pragma once
+#include <memory>
+#include <map>
+
+struct type_mgr;
+
+struct type {
+    virtual ~type() = default;
+
+    virtual void print(const type_mgr& mgr, std::ostream& to) const = 0;
+};
+
+using type_ptr = std::shared_ptr<type>;
+
+struct type_var : public type {
+    std::string name;
+
+    type_var(std::string n)
+        : name(std::move(n)) {}
+
+    void print(const type_mgr& mgr, std::ostream& to) const;
+};
+
+struct type_base : public type {
+    std::string name;
+
+    type_base(std::string n) 
+        : name(std::move(n)) {}
+
+    void print(const type_mgr& mgr, std::ostream& to) const;
+};
+
+struct type_arr : public type {
+    type_ptr left;
+    type_ptr right;
+
+    type_arr(type_ptr l, type_ptr r)
+        : left(std::move(l)), right(std::move(r)) {}
+
+    void print(const type_mgr& mgr, std::ostream& to) const;
+};
+
+struct type_mgr {
+    int last_id = 0;
+    std::map<std::string, type_ptr> types;
+
+    std::string new_type_name();
+    type_ptr new_type();
+    type_ptr new_arrow_type();
+
+    void unify(type_ptr l, type_ptr r);
+    type_ptr resolve(type_ptr t, type_var*& var);
+    void bind(const std::string& s, type_ptr t);
+};
--- a/code/compiler/06/CMakeLists.txt
+++ b/code/compiler/06/CMakeLists.txt
@ -0,0 +1,28 @@
+cmake_minimum_required(VERSION 3.1)
+project(compiler)
+
+find_package(BISON)
+find_package(FLEX)
+bison_target(parser
+    ${CMAKE_CURRENT_SOURCE_DIR}/parser.y
+    ${CMAKE_CURRENT_BINARY_DIR}/parser.cpp
+    COMPILE_FLAGS "-d")
+flex_target(scanner
+    ${CMAKE_CURRENT_SOURCE_DIR}/scanner.l
+    ${CMAKE_CURRENT_BINARY_DIR}/scanner.cpp)
+add_flex_bison_dependency(scanner parser)
+
+add_executable(compiler
+    ast.cpp ast.hpp definition.cpp
+    type_env.cpp type_env.hpp
+    env.cpp env.hpp
+    type.cpp type.hpp
+    error.cpp error.hpp
+    binop.cpp binop.hpp
+    instruction.cpp instruction.hpp
+    ${BISON_parser_OUTPUTS}
+    ${FLEX_scanner_OUTPUTS}
+    main.cpp
+)
+target_include_directories(compiler PUBLIC ${CMAKE_CURRENT_SOURCE_DIR})
+target_include_directories(compiler PUBLIC ${CMAKE_CURRENT_BINARY_DIR})
--- a/code/compiler/06/ast.cpp
+++ b/code/compiler/06/ast.cpp
@ -0,0 +1,262 @@
+#include "ast.hpp"
+#include <ostream>
+#include "error.hpp"
+
+static void print_indent(int n, std::ostream& to) {
+    while(n--) to << "  ";
+}
+
+type_ptr ast::typecheck_common(type_mgr& mgr, const type_env& env) {
+    node_type = typecheck(mgr, env);
+    return node_type;
+}
+
+void ast::resolve_common(const type_mgr& mgr) {
+    type_var* var;
+    type_ptr resolved_type = mgr.resolve(node_type, var);
+    if(var) throw type_error("ambiguously typed program");
+
+    resolve(mgr);
+    node_type = std::move(resolved_type);
+}
+
+void ast_int::print(int indent, std::ostream& to) const {
+    print_indent(indent, to);
+    to << "INT: " << value << std::endl;
+}
+
+type_ptr ast_int::typecheck(type_mgr& mgr, const type_env& env) const {
+    return type_ptr(new type_base("Int"));
+}
+
+void ast_int::resolve(const type_mgr& mgr) const {
+    
+}
+
+void ast_int::compile(const env_ptr& env, std::vector<instruction_ptr>& into) const {
+    into.push_back(instruction_ptr(new instruction_pushint(value)));
+}
+
+void ast_lid::print(int indent, std::ostream& to) const {
+    print_indent(indent, to);
+    to << "LID: " << id << std::endl;
+}
+
+type_ptr ast_lid::typecheck(type_mgr& mgr, const type_env& env) const {
+    return env.lookup(id);
+}
+
+void ast_lid::resolve(const type_mgr& mgr) const {
+
+}
+
+void ast_lid::compile(const env_ptr& env, std::vector<instruction_ptr>& into) const {
+    into.push_back(instruction_ptr(
+        env->has_variable(id) ?
+            (instruction*) new instruction_push(env->get_offset(id)) :
+            (instruction*) new instruction_pushglobal(id)));
+}
+
+void ast_uid::print(int indent, std::ostream& to) const {
+    print_indent(indent, to);
+    to << "UID: " << id << std::endl;
+}
+
+type_ptr ast_uid::typecheck(type_mgr& mgr, const type_env& env) const {
+    return env.lookup(id);
+}
+
+void ast_uid::resolve(const type_mgr& mgr) const {
+
+}
+
+void ast_uid::compile(const env_ptr& env, std::vector<instruction_ptr>& into) const {
+    into.push_back(instruction_ptr(new instruction_pushglobal(id)));
+}
+
+void ast_binop::print(int indent, std::ostream& to) const {
+    print_indent(indent, to);
+    to << "BINOP: " << op_name(op) << std::endl;
+    left->print(indent + 1, to);
+    right->print(indent + 1, to);
+}
+
+type_ptr ast_binop::typecheck(type_mgr& mgr, const type_env& env) const {
+    type_ptr ltype = left->typecheck_common(mgr, env);
+    type_ptr rtype = right->typecheck_common(mgr, env);
+    type_ptr ftype = env.lookup(op_name(op));
+    if(!ftype) throw type_error(std::string("unknown binary operator ") + op_name(op));
+
+    type_ptr return_type = mgr.new_type();
+    type_ptr arrow_one = type_ptr(new type_arr(rtype, return_type));
+    type_ptr arrow_two = type_ptr(new type_arr(ltype, arrow_one));
+
+    mgr.unify(arrow_two, ftype);
+    return return_type;
+}
+
+void ast_binop::resolve(const type_mgr& mgr) const {
+    left->resolve_common(mgr);
+    right->resolve_common(mgr);
+}
+
+void ast_binop::compile(const env_ptr& env, std::vector<instruction_ptr>& into) const {
+    right->compile(env, into);
+    left->compile(env_ptr(new env_offset(1, env)), into);
+
+    into.push_back(instruction_ptr(new instruction_pushglobal(op_action(op))));
+    into.push_back(instruction_ptr(new instruction_mkapp()));
+    into.push_back(instruction_ptr(new instruction_mkapp()));
+}
+
+void ast_app::print(int indent, std::ostream& to) const {
+    print_indent(indent, to);
+    to << "APP:" << std::endl;
+    left->print(indent + 1, to);
+    right->print(indent + 1, to);
+}
+
+type_ptr ast_app::typecheck(type_mgr& mgr, const type_env& env) const {
+    type_ptr ltype = left->typecheck_common(mgr, env);
+    type_ptr rtype = right->typecheck_common(mgr, env);
+
+    type_ptr return_type = mgr.new_type();
+    type_ptr arrow = type_ptr(new type_arr(rtype, return_type));
+    mgr.unify(arrow, ltype);
+    return return_type;
+}
+
+void ast_app::resolve(const type_mgr& mgr) const {
+    left->resolve_common(mgr);
+    right->resolve_common(mgr);
+}
+
+void ast_app::compile(const env_ptr& env, std::vector<instruction_ptr>& into) const {
+    right->compile(env, into);
+    left->compile(env_ptr(new env_offset(1, env)), into);
+    into.push_back(instruction_ptr(new instruction_mkapp()));
+}
+
+void ast_case::print(int indent, std::ostream& to) const {
+    print_indent(indent, to);
+    to << "CASE: " << std::endl;
+    for(auto& branch : branches) {
+        print_indent(indent + 1, to);
+        branch->pat->print(to);
+        to << std::endl;
+        branch->expr->print(indent + 2, to);
+    }
+}
+
+type_ptr ast_case::typecheck(type_mgr& mgr, const type_env& env) const {
+    type_var* var;
+    type_ptr case_type = mgr.resolve(of->typecheck_common(mgr, env), var);
+    type_ptr branch_type = mgr.new_type();
+
+    for(auto& branch : branches) {
+        type_env new_env = env.scope();
+        branch->pat->match(case_type, mgr, new_env);
+        type_ptr curr_branch_type = branch->expr->typecheck_common(mgr, new_env);
+        mgr.unify(branch_type, curr_branch_type);
+    }
+
+    case_type = mgr.resolve(case_type, var);
+    if(!dynamic_cast<type_data*>(case_type.get())) {
+        throw type_error("attempting case analysis of non-data type");
+    }
+
+    return branch_type;
+}
+
+void ast_case::resolve(const type_mgr& mgr) const {
+    of->resolve_common(mgr);
+    for(auto& branch : branches) {
+        branch->expr->resolve_common(mgr);
+    }
+}
+
+void ast_case::compile(const env_ptr& env, std::vector<instruction_ptr>& into) const {
+    type_data* type = dynamic_cast<type_data*>(of->node_type.get());
+
+    of->compile(env, into);
+    into.push_back(instruction_ptr(new instruction_eval()));
+
+    instruction_jump* jump_instruction = new instruction_jump();
+    into.push_back(instruction_ptr(jump_instruction));
+    for(auto& branch : branches) {
+        std::vector<instruction_ptr> branch_instructions;
+        pattern_var* vpat;
+        pattern_constr* cpat;
+
+        if((vpat = dynamic_cast<pattern_var*>(branch->pat.get()))) {
+            branch->expr->compile(env_ptr(new env_offset(1, env)), branch_instructions);
+
+            for(auto& constr_pair : type->constructors) {
+                if(jump_instruction->tag_mappings.find(constr_pair.second.tag) !=
+                        jump_instruction->tag_mappings.end())
+                    break;
+
+                jump_instruction->tag_mappings[constr_pair.second.tag] =
+                    jump_instruction->branches.size();
+            }
+            jump_instruction->branches.push_back(std::move(branch_instructions));
+        } else if((cpat = dynamic_cast<pattern_constr*>(branch->pat.get()))) {
+            env_ptr new_env = env;
+            for(auto it = cpat->params.rbegin(); it != cpat->params.rend(); it++) {
+                new_env = env_ptr(new env_var(*it, new_env));
+            }
+
+            branch_instructions.push_back(instruction_ptr(new instruction_split()));
+            branch->expr->compile(new_env, branch_instructions);
+            branch_instructions.push_back(instruction_ptr(new instruction_slide(
+                            cpat->params.size())));
+
+            int new_tag = type->constructors[cpat->constr].tag;
+            if(jump_instruction->tag_mappings.find(new_tag) !=
+                    jump_instruction->tag_mappings.end())
+                throw type_error("technically not a type error: duplicate pattern");
+
+            jump_instruction->tag_mappings[new_tag] =
+                jump_instruction->branches.size();
+            jump_instruction->branches.push_back(std::move(branch_instructions));
+        }
+    }
+
+    for(auto& constr_pair : type->constructors) {
+        if(jump_instruction->tag_mappings.find(constr_pair.second.tag) ==
+                jump_instruction->tag_mappings.end())
+            throw type_error("non-total pattern");
+    }
+}
+
+void pattern_var::print(std::ostream& to) const {
+    to << var;
+}
+
+void pattern_var::match(type_ptr t, type_mgr& mgr, type_env& env) const {
+    env.bind(var, t);
+}
+
+void pattern_constr::print(std::ostream& to) const {
+    to << constr;
+    for(auto& param : params) {
+        to << " " << param;
+    }
+}
+
+void pattern_constr::match(type_ptr t, type_mgr& mgr, type_env& env) const {
+    type_ptr constructor_type = env.lookup(constr);
+    if(!constructor_type) {
+        throw type_error(std::string("pattern using unknown constructor ") + constr);
+    }
+
+    for(int i = 0; i < params.size(); i++) {
+        type_arr* arr = dynamic_cast<type_arr*>(constructor_type.get());
+        if(!arr) throw type_error("too many parameters in constructor pattern");
+
+        env.bind(params[i], arr->left);
+        constructor_type = arr->right;
+    }
+
+    mgr.unify(t, constructor_type);
+}
--- a/code/compiler/06/ast.hpp
+++ b/code/compiler/06/ast.hpp
@ -0,0 +1,197 @@
+#pragma once
+#include <memory>
+#include <vector>
+#include "type.hpp"
+#include "type_env.hpp"
+#include "binop.hpp"
+#include "instruction.hpp"
+#include "env.hpp"
+
+struct ast {
+    type_ptr node_type;
+
+    virtual ~ast() = default;
+
+    virtual void print(int indent, std::ostream& to) const = 0;
+    virtual type_ptr typecheck(type_mgr& mgr, const type_env& env) const = 0;
+    virtual void resolve(const type_mgr& mgr) const = 0;
+    virtual void compile(const env_ptr& env,
+        std::vector<instruction_ptr>& into) const = 0;
+
+    type_ptr typecheck_common(type_mgr& mgr, const type_env& env);
+    void resolve_common(const type_mgr& mgr);
+};
+
+using ast_ptr = std::unique_ptr<ast>;
+
+struct pattern {
+    virtual ~pattern() = default;
+
+    virtual void print(std::ostream& to) const = 0;
+    virtual void match(type_ptr t, type_mgr& mgr, type_env& env) const = 0;
+};
+
+using pattern_ptr = std::unique_ptr<pattern>;
+
+struct branch {
+    pattern_ptr pat;
+    ast_ptr expr;
+
+    branch(pattern_ptr p, ast_ptr a)
+        : pat(std::move(p)), expr(std::move(a)) {}
+};
+
+using branch_ptr = std::unique_ptr<branch>;
+
+struct constructor {
+    std::string name;
+    std::vector<std::string> types;
+    int8_t tag;
+
+    constructor(std::string n, std::vector<std::string> ts)
+        : name(std::move(n)), types(std::move(ts)) {}
+};
+
+using constructor_ptr = std::unique_ptr<constructor>;
+
+struct definition {
+    virtual ~definition() = default;
+    
+    virtual void typecheck_first(type_mgr& mgr, type_env& env) = 0;
+    virtual void typecheck_second(type_mgr& mgr, const type_env& env) const = 0;
+    virtual void resolve(const type_mgr& mgr) = 0;
+    virtual void compile() = 0;
+};
+
+using definition_ptr = std::unique_ptr<definition>;
+
+struct ast_int : public ast {
+    int value;
+
+    explicit ast_int(int v)
+        : value(v) {}
+
+    void print(int indent, std::ostream& to) const;
+    type_ptr typecheck(type_mgr& mgr, const type_env& env) const;
+    void resolve(const type_mgr& mgr) const;
+    void compile(const env_ptr& env, std::vector<instruction_ptr>& into) const;
+};
+
+struct ast_lid : public ast {
+    std::string id;
+
+    explicit ast_lid(std::string i)
+        : id(std::move(i)) {}
+
+    void print(int indent, std::ostream& to) const;
+    type_ptr typecheck(type_mgr& mgr, const type_env& env) const;
+    void resolve(const type_mgr& mgr) const;
+    void compile(const env_ptr& env, std::vector<instruction_ptr>& into) const;
+};
+
+struct ast_uid : public ast {
+    std::string id;
+
+    explicit ast_uid(std::string i)
+        : id(std::move(i)) {}
+
+    void print(int indent, std::ostream& to) const;
+    type_ptr typecheck(type_mgr& mgr, const type_env& env) const;
+    void resolve(const type_mgr& mgr) const;
+    void compile(const env_ptr& env, std::vector<instruction_ptr>& into) const;
+};
+
+struct ast_binop : public ast {
+    binop op;  
+    ast_ptr left;
+    ast_ptr right;
+
+    ast_binop(binop o, ast_ptr l, ast_ptr r)
+        : op(o), left(std::move(l)), right(std::move(r)) {}
+
+    void print(int indent, std::ostream& to) const;
+    type_ptr typecheck(type_mgr& mgr, const type_env& env) const;
+    void resolve(const type_mgr& mgr) const;
+    void compile(const env_ptr& env, std::vector<instruction_ptr>& into) const;
+};
+
+struct ast_app : public ast {
+    ast_ptr left;
+    ast_ptr right;
+
+    ast_app(ast_ptr l, ast_ptr r)
+        : left(std::move(l)), right(std::move(r)) {}
+
+    void print(int indent, std::ostream& to) const;
+    type_ptr typecheck(type_mgr& mgr, const type_env& env) const;
+    void resolve(const type_mgr& mgr) const;
+    void compile(const env_ptr& env, std::vector<instruction_ptr>& into) const;
+};
+
+struct ast_case : public ast {
+    ast_ptr of;
+    std::vector<branch_ptr> branches;
+
+    ast_case(ast_ptr o, std::vector<branch_ptr> b)
+        : of(std::move(o)), branches(std::move(b)) {}
+
+    void print(int indent, std::ostream& to) const;
+    type_ptr typecheck(type_mgr& mgr, const type_env& env) const;
+    void resolve(const type_mgr& mgr) const;
+    void compile(const env_ptr& env, std::vector<instruction_ptr>& into) const;
+};
+
+struct pattern_var : public pattern {
+    std::string var;
+
+    pattern_var(std::string v)
+        : var(std::move(v)) {}
+
+    void print(std::ostream &to) const;
+    void match(type_ptr t, type_mgr& mgr, type_env& env) const;
+};
+
+struct pattern_constr : public pattern {
+    std::string constr;
+    std::vector<std::string> params;
+
+    pattern_constr(std::string c, std::vector<std::string> p)
+        : constr(std::move(c)), params(std::move(p)) {}
+
+    void print(std::ostream &to) const;
+    void match(type_ptr t, type_mgr&, type_env& env) const;
+};
+
+struct definition_defn : public definition {
+    std::string name;
+    std::vector<std::string> params;
+    ast_ptr body;
+
+    type_ptr return_type;
+    std::vector<type_ptr> param_types;
+
+    std::vector<instruction_ptr> instructions;
+
+    definition_defn(std::string n, std::vector<std::string> p, ast_ptr b)
+        : name(std::move(n)), params(std::move(p)), body(std::move(b)) {
+
+    }
+
+    void typecheck_first(type_mgr& mgr, type_env& env);
+    void typecheck_second(type_mgr& mgr, const type_env& env) const;
+    void resolve(const type_mgr& mgr);
+    void compile();
+};
+
+struct definition_data : public definition {
+    std::string name;
+    std::vector<constructor_ptr> constructors;
+
+    definition_data(std::string n, std::vector<constructor_ptr> cs)
+        : name(std::move(n)), constructors(std::move(cs)) {}
+
+    void typecheck_first(type_mgr& mgr, type_env& env);
+    void typecheck_second(type_mgr& mgr, const type_env& env) const;
+    void resolve(const type_mgr& mgr);
+    void compile();
+};
--- a/code/compiler/06/binop.cpp
+++ b/code/compiler/06/binop.cpp
@ -0,0 +1,21 @@
+#include "binop.hpp"
+
+std::string op_name(binop op) {
+    switch(op) {
+        case PLUS: return "+";
+        case MINUS: return "-";
+        case TIMES: return "*";
+        case DIVIDE: return "/";
+    }
+    return "??";
+}
+
+std::string op_action(binop op) {
+    switch(op) {
+        case PLUS: return "plus";
+        case MINUS: return "minus";
+        case TIMES: return "times";
+        case DIVIDE: return "divide";
+    }
+    return "??";
+}
--- a/code/compiler/06/binop.hpp
+++ b/code/compiler/06/binop.hpp
@ -0,0 +1,12 @@
+#pragma once
+#include <string>
+
+enum binop {
+    PLUS,
+    MINUS,
+    TIMES,
+    DIVIDE
+};
+
+std::string op_name(binop op);
+std::string op_action(binop op);
--- a/code/compiler/06/definition.cpp
+++ b/code/compiler/06/definition.cpp
@ -0,0 +1,83 @@
+#include "ast.hpp"
+#include "error.hpp"
+
+void definition_defn::typecheck_first(type_mgr& mgr, type_env& env) {
+    return_type = mgr.new_type();
+    type_ptr full_type = return_type;
+
+    for(auto it = params.rbegin(); it != params.rend(); it++) {
+        type_ptr param_type = mgr.new_type();
+        full_type = type_ptr(new type_arr(param_type, full_type));
+        param_types.push_back(param_type);
+    }
+
+    env.bind(name, full_type);
+}
+
+void definition_defn::typecheck_second(type_mgr& mgr, const type_env& env) const {
+    type_env new_env = env.scope();
+    auto param_it = params.begin();
+    auto type_it = param_types.rbegin();
+
+    while(param_it != params.end() && type_it != param_types.rend()) {
+        new_env.bind(*param_it, *type_it);
+        param_it++;
+        type_it++;
+    }
+
+    type_ptr body_type = body->typecheck_common(mgr, new_env);
+    mgr.unify(return_type, body_type);
+}
+
+void definition_defn::resolve(const type_mgr& mgr) {
+    type_var* var;
+    body->resolve_common(mgr);
+
+    return_type = mgr.resolve(return_type, var);
+    if(var) throw type_error("ambiguously typed program");
+    for(auto& param_type : param_types) {
+        param_type = mgr.resolve(param_type, var);
+        if(var) throw type_error("ambiguously typed program");
+    }
+}
+
+void definition_defn::compile() {
+    env_ptr new_env = env_ptr(new env_offset(0, nullptr));
+    for(auto it = params.rbegin(); it != params.rend(); it++) {
+        new_env = env_ptr(new env_var(*it, new_env));
+    }
+    body->compile(new_env, instructions);
+    instructions.push_back(instruction_ptr(new instruction_update(params.size())));
+    instructions.push_back(instruction_ptr(new instruction_pop(params.size())));
+}
+
+void definition_data::typecheck_first(type_mgr& mgr, type_env& env) {
+    type_data* this_type = new type_data(name);
+    type_ptr return_type = type_ptr(this_type);
+    int next_tag = 0;
+
+    for(auto& constructor : constructors) {
+        constructor->tag = next_tag;
+        this_type->constructors[constructor->name] = { next_tag++ };
+
+        type_ptr full_type = return_type;
+        for(auto it = constructor->types.rbegin(); it != constructor->types.rend(); it++) {
+            type_ptr type = type_ptr(new type_base(*it));
+            full_type = type_ptr(new type_arr(type, full_type));
+        }
+
+        env.bind(constructor->name, full_type);
+    }
+}
+
+void definition_data::typecheck_second(type_mgr& mgr, const type_env& env) const {
+    // Nothing
+}
+
+void definition_data::resolve(const type_mgr& mgr) {
+    // Nothing
+}
+
+void definition_data::compile() {
+
+}
--- a/code/compiler/06/env.cpp
+++ b/code/compiler/06/env.cpp
@ -0,0 +1,23 @@
+#include "env.hpp"
+
+int env_var::get_offset(const std::string& name) const {
+    if(name == this->name) return 0;
+    if(parent) return parent->get_offset(name) + 1;
+    throw 0;
+}
+
+bool env_var::has_variable(const std::string& name) const {
+    if(name == this->name) return true;
+    if(parent) return parent->has_variable(name);
+    return false;
+}
+
+int env_offset::get_offset(const std::string& name) const {
+    if(parent) return parent->get_offset(name) + offset;
+    throw 0;
+}
+
+bool env_offset::has_variable(const std::string& name) const {
+    if(parent) return parent->has_variable(name);
+    return false;
+}
--- a/code/compiler/06/env.hpp
+++ b/code/compiler/06/env.hpp
@ -0,0 +1,34 @@
+#pragma once
+#include <memory>
+#include <string>
+
+struct env {
+    virtual ~env() = default;
+
+    virtual int get_offset(const std::string& name) const = 0;
+    virtual bool has_variable(const std::string& name) const = 0;
+};
+
+using env_ptr = std::shared_ptr<env>;
+
+struct env_var : public env {
+    std::string name;
+    env_ptr parent;
+
+    env_var(std::string& n, env_ptr p)
+        : name(std::move(n)), parent(std::move(p)) {}
+
+    int get_offset(const std::string& name) const;
+    bool has_variable(const std::string& name) const;
+};
+
+struct env_offset : public env {
+    int offset;
+    env_ptr parent;
+
+    env_offset(int o, env_ptr p)
+        : offset(o), parent(std::move(p)) {}
+
+    int get_offset(const std::string& name) const;
+    bool has_variable(const std::string& name) const;
+};
--- a/code/compiler/06/error.cpp
+++ b/code/compiler/06/error.cpp
@ -0,0 +1,5 @@
+#include "error.hpp"
+
+const char* type_error::what() const noexcept {
+    return "an error occured while checking the types of the program";
+}
--- a/code/compiler/06/error.hpp
+++ b/code/compiler/06/error.hpp
@ -0,0 +1,21 @@
+#pragma once
+#include <exception>
+#include "type.hpp"
+
+struct type_error : std::exception {
+    std::string description;
+
+    type_error(std::string d)
+        : description(std::move(d)) {}
+
+    const char* what() const noexcept override;
+};
+
+struct unification_error : public type_error {
+    type_ptr left;
+    type_ptr right;
+
+    unification_error(type_ptr l, type_ptr r)
+        : left(std::move(l)), right(std::move(r)), 
+            type_error("failed to unify types") {}
+};
--- a/code/compiler/06/examples/bad1.txt
+++ b/code/compiler/06/examples/bad1.txt
@ -0,0 +1,2 @@
+data Bool = { True, False }
+defn main = { 3 + True }
--- a/code/compiler/06/examples/bad2.txt
+++ b/code/compiler/06/examples/bad2.txt
@ -0,0 +1 @@
+defn main = { 1 2 3 4 5 }
--- a/code/compiler/06/examples/bad3.txt
+++ b/code/compiler/06/examples/bad3.txt
@ -0,0 +1,8 @@
+data List = { Nil, Cons Int List }
+
+defn head l = {
+    case l of {
+        Nil -> { 0 }
+        Cons x y z -> { x }
+    }
+}
--- a/code/compiler/06/examples/works1.txt
+++ b/code/compiler/06/examples/works1.txt
@ -0,0 +1,2 @@
+defn main = { plus 320 6 }
+defn plus x y = { x + y }
--- a/code/compiler/06/examples/works2.txt
+++ b/code/compiler/06/examples/works2.txt
@ -0,0 +1,3 @@
+defn add x y = { x + y }
+defn double x = { add x x }
+defn main = { double 163 }
--- a/code/compiler/06/examples/works3.txt
+++ b/code/compiler/06/examples/works3.txt
@ -0,0 +1,7 @@
+data List = { Nil, Cons Int List }
+defn length l = {
+    case l of {
+        Nil -> { 0 }
+        Cons x xs -> { 1 + length xs }
+    }
+}
--- a/code/compiler/06/instruction.cpp
+++ b/code/compiler/06/instruction.cpp
@ -0,0 +1,83 @@
+#include "instruction.hpp"
+
+static void print_indent(int n, std::ostream& to) {
+    while(n--) to << "  ";
+}
+
+void instruction_pushint::print(int indent, std::ostream& to) const {
+    print_indent(indent, to);
+    to << "PushInt(" << value << ")" << std::endl;
+}
+
+void instruction_pushglobal::print(int indent, std::ostream& to) const {
+    print_indent(indent, to);
+    to << "PushGlobal(" << name << ")" << std::endl;
+}
+
+void instruction_push::print(int indent, std::ostream& to) const {
+    print_indent(indent, to);
+    to << "Push(" << offset << ")" << std::endl;
+}
+
+void instruction_pop::print(int indent, std::ostream& to) const {
+    print_indent(indent, to);
+    to << "Pop(" << count << ")" << std::endl;
+}
+
+void instruction_mkapp::print(int indent, std::ostream& to) const {
+    print_indent(indent, to);
+    to << "MkApp()" << std::endl;
+}
+
+void instruction_update::print(int indent, std::ostream& to) const {
+    print_indent(indent, to);
+    to << "Update(" << offset << ")" << std::endl;
+}
+
+void instruction_pack::print(int indent, std::ostream& to) const {
+    print_indent(indent, to);
+    to << "Pack(" << tag << ", " << size << ")" << std::endl;
+}
+
+void instruction_split::print(int indent, std::ostream& to) const {
+    print_indent(indent, to);
+    to << "Split()" << std::endl;
+}
+
+void instruction_jump::print(int indent, std::ostream& to) const {
+    print_indent(indent, to);
+    to << "Jump(" << std::endl;
+    for(auto& instruction_set : branches) {
+        for(auto& instruction : instruction_set) {
+            instruction->print(indent + 2, to);
+        }
+        to << std::endl;
+    }
+    print_indent(indent, to);
+    to << ")" << std::endl;
+}
+
+void instruction_slide::print(int indent, std::ostream& to) const {
+    print_indent(indent, to);
+    to << "Slide(" << offset << ")" << std::endl;
+}
+
+void instruction_binop::print(int indent, std::ostream& to) const {
+    print_indent(indent, to);
+    to << "BinOp(" << op_action(op) << ")" << std::endl;
+}
+
+void instruction_eval::print(int indent, std::ostream& to) const {
+    print_indent(indent, to);
+    to << "Eval()" << std::endl;
+}
+
+void instruction_alloc::print(int indent, std::ostream& to) const {
+    print_indent(indent, to);
+    to << "Alloc(" << amount << ")" << std::endl;
+}
+
+void instruction_unwind::print(int indent, std::ostream& to) const {
+    print_indent(indent, to);
+    to << "Unwind()" << std::endl;
+}
--- a/code/compiler/06/instruction.hpp
+++ b/code/compiler/06/instruction.hpp
@ -0,0 +1,120 @@
+#pragma once
+#include <string>
+#include <memory>
+#include <vector>
+#include <map>
+#include <ostream>
+#include "binop.hpp"
+
+struct instruction {
+    virtual ~instruction() = default;
+
+    virtual void print(int indent, std::ostream& to) const = 0;
+};
+
+using instruction_ptr = std::unique_ptr<instruction>;
+
+struct instruction_pushint : public instruction {
+    int value;
+
+    instruction_pushint(int v)
+        : value(v) {}
+
+    void print(int indent, std::ostream& to) const;
+};
+
+struct instruction_pushglobal : public instruction {
+    std::string name;
+
+    instruction_pushglobal(std::string n)
+        : name(std::move(n)) {}
+
+    void print(int indent, std::ostream& to) const;
+};
+
+struct instruction_push : public instruction {
+    int offset;
+
+    instruction_push(int o)
+        : offset(o) {}
+
+    void print(int indent, std::ostream& to) const;
+};
+
+struct instruction_pop : public instruction {
+    int count;
+
+    instruction_pop(int c)
+        : count(c) {}
+
+    void print(int indent, std::ostream& to) const;
+};
+
+struct instruction_mkapp : public instruction {
+    void print(int indent, std::ostream& to) const;
+};
+
+struct instruction_update : public instruction {
+    int offset;
+
+    instruction_update(int o)
+        : offset(o) {}
+
+    void print(int indent, std::ostream& to) const;
+};
+
+struct instruction_pack : public instruction {
+    int tag;
+    int size;
+
+    instruction_pack(int t, int s)
+        : tag(t), size(s) {}
+
+    void print(int indent, std::ostream& to) const;
+};
+
+struct instruction_split : public instruction {
+    void print(int indent, std::ostream& to) const;
+};
+
+struct instruction_jump : public instruction {
+    std::vector<std::vector<instruction_ptr>> branches;
+    std::map<int, int> tag_mappings;
+
+    void print(int indent, std::ostream& to) const;
+};
+
+struct instruction_slide : public instruction {
+    int offset;
+
+    instruction_slide(int o)
+        : offset(o) {}
+
+    void print(int indent, std::ostream& to) const;
+};
+
+struct instruction_binop : public instruction {
+    binop op;
+
+    instruction_binop(binop o)
+        : op(o) {}
+
+    void print(int indent, std::ostream& to) const;
+};
+
+struct instruction_eval : public instruction {
+    void print(int indent, std::ostream& to) const;
+};
+
+struct instruction_alloc : public instruction {
+    int amount;
+
+    instruction_alloc(int a)
+        : amount(a) {}
+
+    void print(int indent, std::ostream& to) const;
+};
+
+struct instruction_unwind : public instruction {
+    void print(int indent, std::ostream& to) const;
+};
--- a/code/compiler/06/main.cpp
+++ b/code/compiler/06/main.cpp
@ -0,0 +1,88 @@
+#include "ast.hpp"
+#include <iostream>
+#include "parser.hpp"
+#include "error.hpp"
+#include "type.hpp"
+
+void yy::parser::error(const std::string& msg) {
+    std::cout << "An error occured: " << msg << std::endl;
+}
+
+extern std::vector<definition_ptr> program;
+
+void typecheck_program(
+        const std::vector<definition_ptr>& prog,
+        type_mgr& mgr, type_env& env) {
+    type_ptr int_type = type_ptr(new type_base("Int")); 
+    type_ptr binop_type = type_ptr(new type_arr(
+                int_type,
+                type_ptr(new type_arr(int_type, int_type))));
+
+    env.bind("+", binop_type);
+    env.bind("-", binop_type);
+    env.bind("*", binop_type);
+    env.bind("/", binop_type);
+
+    for(auto& def : prog) {
+        def->typecheck_first(mgr, env);
+    }
+
+    for(auto& def : prog) {
+        def->typecheck_second(mgr, env);
+    }
+
+    for(auto& pair : env.names) {
+        std::cout << pair.first << ": ";
+        pair.second->print(mgr, std::cout);
+        std::cout << std::endl;
+    }
+
+    for(auto& def : prog) {
+        def->resolve(mgr);
+    }
+}
+
+void compile_program(const std::vector<definition_ptr>& prog) {
+    for(auto& def : prog) {
+        def->compile();
+
+        definition_defn* defn = dynamic_cast<definition_defn*>(def.get());
+        if(!defn) continue;
+        for(auto& instruction : defn->instructions) {
+            instruction->print(0, std::cout);
+        }
+        std::cout << std::endl;
+    }
+}
+
+int main() {
+    yy::parser parser;
+    type_mgr mgr;
+    type_env env;
+
+    parser.parse();
+    for(auto& definition : program) {
+        definition_defn* def = dynamic_cast<definition_defn*>(definition.get());
+        if(!def) continue;
+
+        std::cout << def->name;
+        for(auto& param : def->params) std::cout << " " << param;
+        std::cout << ":" << std::endl;
+
+        def->body->print(1, std::cout);
+    }
+    try {
+        typecheck_program(program, mgr, env);
+        compile_program(program);
+    } catch(unification_error& err) {
+        std::cout << "failed to unify types: " << std::endl;
+        std::cout << "  (1) \033[34m";
+        err.left->print(mgr, std::cout);
+        std::cout << "\033[0m" << std::endl;
+        std::cout << "  (2) \033[32m";
+        err.right->print(mgr, std::cout);
+        std::cout << "\033[0m" << std::endl;
+    } catch(type_error& err) {
+        std::cout << "failed to type check program: " << err.description << std::endl;
+    }
+}
--- a/code/compiler/06/parser.y
+++ b/code/compiler/06/parser.y
@ -0,0 +1,140 @@
+%{
+#include <string>
+#include <iostream>
+#include "ast.hpp"
+#include "parser.hpp"
+
+std::vector<definition_ptr> program;
+extern yy::parser::symbol_type yylex();
+
+%}
+
+%token PLUS
+%token TIMES
+%token MINUS
+%token DIVIDE
+%token <int> INT
+%token DEFN
+%token DATA
+%token CASE
+%token OF
+%token OCURLY
+%token CCURLY
+%token OPAREN
+%token CPAREN
+%token COMMA
+%token ARROW
+%token EQUAL
+%token <std::string> LID
+%token <std::string> UID
+
+%language "c++"
+%define api.value.type variant
+%define api.token.constructor
+
+%type <std::vector<std::string>> lowercaseParams uppercaseParams
+%type <std::vector<definition_ptr>> program definitions
+%type <std::vector<branch_ptr>> branches
+%type <std::vector<constructor_ptr>> constructors
+%type <ast_ptr> aAdd aMul case app appBase
+%type <definition_ptr> definition defn data 
+%type <branch_ptr> branch
+%type <pattern_ptr> pattern
+%type <constructor_ptr> constructor
+
+%start program
+
+%%
+
+program
+    : definitions { program = std::move($1); }
+    ;
+
+definitions
+    : definitions definition { $$ = std::move($1); $$.push_back(std::move($2)); }
+    | definition { $$ = std::vector<definition_ptr>(); $$.push_back(std::move($1)); }
+    ;
+
+definition
+    : defn { $$ = std::move($1); }
+    | data { $$ = std::move($1); }
+    ;
+
+defn
+    : DEFN LID lowercaseParams EQUAL OCURLY aAdd CCURLY
+        { $$ = definition_ptr(
+            new definition_defn(std::move($2), std::move($3), std::move($6))); }
+    ;
+
+lowercaseParams
+    : %empty { $$ = std::vector<std::string>(); }
+    | lowercaseParams LID { $$ = std::move($1); $$.push_back(std::move($2)); }
+    ;
+
+uppercaseParams
+    : %empty { $$ = std::vector<std::string>(); }
+    | uppercaseParams UID { $$ = std::move($1); $$.push_back(std::move($2)); }
+    ;
+
+aAdd
+    : aAdd PLUS aMul { $$ = ast_ptr(new ast_binop(PLUS, std::move($1), std::move($3))); }
+    | aAdd MINUS aMul { $$ = ast_ptr(new ast_binop(MINUS, std::move($1), std::move($3))); }
+    | aMul { $$ = std::move($1); }
+    ;
+
+aMul
+    : aMul TIMES app { $$ = ast_ptr(new ast_binop(TIMES, std::move($1), std::move($3))); }
+    | aMul DIVIDE app { $$ = ast_ptr(new ast_binop(DIVIDE, std::move($1), std::move($3))); }
+    | app { $$ = std::move($1); }
+    ;
+
+app
+    : app appBase { $$ = ast_ptr(new ast_app(std::move($1), std::move($2))); }
+    | appBase { $$ = std::move($1); }
+    ;
+
+appBase
+    : INT { $$ = ast_ptr(new ast_int($1)); }
+    | LID { $$ = ast_ptr(new ast_lid(std::move($1))); }
+    | UID { $$ = ast_ptr(new ast_uid(std::move($1))); }
+    | OPAREN aAdd CPAREN { $$ = std::move($2); }
+    | case { $$ = std::move($1); }
+    ;
+
+case
+    : CASE aAdd OF OCURLY branches CCURLY 
+        { $$ = ast_ptr(new ast_case(std::move($2), std::move($5))); }
+    ;
+
+branches
+    : branches branch { $$ = std::move($1); $$.push_back(std::move($2)); }
+    | branch { $$ = std::vector<branch_ptr>(); $$.push_back(std::move($1));}
+    ;
+
+branch
+    : pattern ARROW OCURLY aAdd CCURLY
+        { $$ = branch_ptr(new branch(std::move($1), std::move($4))); }
+    ;
+
+pattern
+    : LID { $$ = pattern_ptr(new pattern_var(std::move($1))); }
+    | UID lowercaseParams
+        { $$ = pattern_ptr(new pattern_constr(std::move($1), std::move($2))); }
+    ;
+
+data
+    : DATA UID EQUAL OCURLY constructors CCURLY
+        { $$ = definition_ptr(new definition_data(std::move($2), std::move($5))); }
+    ;
+
+constructors
+    : constructors COMMA constructor { $$ = std::move($1); $$.push_back(std::move($3)); }
+    | constructor
+        { $$ = std::vector<constructor_ptr>(); $$.push_back(std::move($1)); }
+    ;
+
+constructor
+    : UID uppercaseParams
+        { $$ = constructor_ptr(new constructor(std::move($1), std::move($2))); }
+    ;
+
--- a/code/compiler/06/scanner.l
+++ b/code/compiler/06/scanner.l
@ -0,0 +1,34 @@
+%option noyywrap
+
+%{
+#include <iostream>
+#include "ast.hpp"
+#include "parser.hpp"
+
+#define YY_DECL yy::parser::symbol_type yylex()
+
+%}
+
+%%
+
+[ \n]+ {}
+\+ { return yy::parser::make_PLUS(); }
+\* { return yy::parser::make_TIMES(); }
+- { return yy::parser::make_MINUS(); }
+\/ { return yy::parser::make_DIVIDE(); }
+[0-9]+ { return yy::parser::make_INT(atoi(yytext)); }
+defn { return yy::parser::make_DEFN(); }
+data { return yy::parser::make_DATA(); }
+case { return yy::parser::make_CASE(); }
+of { return yy::parser::make_OF(); }
+\{ { return yy::parser::make_OCURLY(); }
+\} { return yy::parser::make_CCURLY(); }
+\( { return yy::parser::make_OPAREN(); }
+\) { return yy::parser::make_CPAREN(); }
+,  { return yy::parser::make_COMMA(); }
+-> { return yy::parser::make_ARROW(); }
+= { return yy::parser::make_EQUAL(); }
+[a-z][a-zA-Z]* { return yy::parser::make_LID(std::string(yytext)); }
+[A-Z][a-zA-Z]* { return yy::parser::make_UID(std::string(yytext)); }
+
+%%
--- a/code/compiler/06/type.cpp
+++ b/code/compiler/06/type.cpp
@ -0,0 +1,99 @@
+#include "type.hpp"
+#include <sstream>
+#include <algorithm>
+#include "error.hpp"
+
+void type_var::print(const type_mgr& mgr, std::ostream& to) const {
+    auto it = mgr.types.find(name);
+    if(it != mgr.types.end()) {
+        it->second->print(mgr, to);
+    } else {
+        to << name;
+    }
+}
+
+void type_base::print(const type_mgr& mgr, std::ostream& to) const {
+    to << name;
+}
+
+void type_arr::print(const type_mgr& mgr, std::ostream& to) const {
+    left->print(mgr, to);
+    to << " -> (";
+    right->print(mgr, to);
+    to << ")";
+}
+
+std::string type_mgr::new_type_name() {
+    int temp = last_id++;
+    std::string str = "";
+
+    while(temp != -1) {
+        str += (char) ('a' + (temp % 26));
+        temp = temp / 26 - 1;
+    }
+
+    std::reverse(str.begin(), str.end());
+    return str;
+}
+
+type_ptr type_mgr::new_type() {
+    return type_ptr(new type_var(new_type_name()));
+}
+
+type_ptr type_mgr::new_arrow_type() {
+    return type_ptr(new type_arr(new_type(), new_type()));
+}
+
+type_ptr type_mgr::resolve(type_ptr t, type_var*& var) const {
+    type_var* cast;
+
+    var = nullptr;
+    while((cast = dynamic_cast<type_var*>(t.get()))) {
+        auto it = types.find(cast->name);
+
+        if(it == types.end()) {
+            var = cast;
+            break;
+        }
+        t = it->second;
+    }
+
+    return t;
+}
+
+void type_mgr::unify(type_ptr l, type_ptr r) {
+    type_var* lvar;
+    type_var* rvar;
+    type_arr* larr;
+    type_arr* rarr;
+    type_base* lid;
+    type_base* rid;
+
+    l = resolve(l, lvar);
+    r = resolve(r, rvar);
+
+    if(lvar) {
+        bind(lvar->name, r);
+        return;
+    } else if(rvar) {
+        bind(rvar->name, l);
+        return;
+    } else if((larr = dynamic_cast<type_arr*>(l.get())) &&
+            (rarr = dynamic_cast<type_arr*>(r.get()))) {
+        unify(larr->left, rarr->left);
+        unify(larr->right, rarr->right);
+        return;
+    } else if((lid = dynamic_cast<type_base*>(l.get())) &&
+            (rid = dynamic_cast<type_base*>(r.get()))) {
+        if(lid->name == rid->name) return;
+    }
+
+    throw unification_error(l, r);
+}
+
+void type_mgr::bind(const std::string& s, type_ptr t) {
+    type_var* other = dynamic_cast<type_var*>(t.get());
+    
+    if(other && other->name == s) return;
+    types[s] = t;
+}
--- a/code/compiler/06/type.hpp
+++ b/code/compiler/06/type.hpp
@ -0,0 +1,65 @@
+#pragma once
+#include <memory>
+#include <map>
+
+struct type_mgr;
+
+struct type {
+    virtual ~type() = default;
+
+    virtual void print(const type_mgr& mgr, std::ostream& to) const = 0;
+};
+
+using type_ptr = std::shared_ptr<type>;
+
+struct type_var : public type {
+    std::string name;
+
+    type_var(std::string n)
+        : name(std::move(n)) {}
+
+    void print(const type_mgr& mgr, std::ostream& to) const;
+};
+
+struct type_base : public type {
+    std::string name;
+
+    type_base(std::string n) 
+        : name(std::move(n)) {}
+
+    void print(const type_mgr& mgr, std::ostream& to) const;
+};
+
+struct type_data : public type_base {
+    struct constructor {
+        int tag;
+    };
+
+    std::map<std::string, constructor> constructors;
+
+    type_data(std::string n)
+        : type_base(std::move(n)) {}
+};
+
+struct type_arr : public type {
+    type_ptr left;
+    type_ptr right;
+
+    type_arr(type_ptr l, type_ptr r)
+        : left(std::move(l)), right(std::move(r)) {}
+
+    void print(const type_mgr& mgr, std::ostream& to) const;
+};
+
+struct type_mgr {
+    int last_id = 0;
+    std::map<std::string, type_ptr> types;
+
+    std::string new_type_name();
+    type_ptr new_type();
+    type_ptr new_arrow_type();
+
+    void unify(type_ptr l, type_ptr r);
+    type_ptr resolve(type_ptr t, type_var*& var) const;
+    void bind(const std::string& s, type_ptr t);
+};
--- a/code/compiler/06/type_env.cpp
+++ b/code/compiler/06/type_env.cpp
@ -0,0 +1,16 @@
+#include "type_env.hpp"
+
+type_ptr type_env::lookup(const std::string& name) const {
+    auto it = names.find(name);
+    if(it != names.end()) return it->second;
+    if(parent) return parent->lookup(name);
+    return nullptr;
+}
+
+void type_env::bind(const std::string& name, type_ptr t) {
+    names[name] = t;
+}
+
+type_env type_env::scope() const {
+    return type_env(this);
+}
--- a/code/compiler/06/type_env.hpp
+++ b/code/compiler/06/type_env.hpp
@ -0,0 +1,16 @@
+#pragma once
+#include <map>
+#include "type.hpp"
+
+struct type_env {
+    std::map<std::string, type_ptr> names;
+    type_env const* parent = nullptr;
+
+    type_env(type_env const* p)
+        : parent(p) {}
+    type_env() : type_env(nullptr) {}
+
+    type_ptr lookup(const std::string& name) const;
+    void bind(const std::string& name, type_ptr t);
+    type_env scope() const;
+};
--- a/code/compiler/07/CMakeLists.txt
+++ b/code/compiler/07/CMakeLists.txt
@ -0,0 +1,28 @@
+cmake_minimum_required(VERSION 3.1)
+project(compiler)
+
+find_package(BISON)
+find_package(FLEX)
+bison_target(parser
+    ${CMAKE_CURRENT_SOURCE_DIR}/parser.y
+    ${CMAKE_CURRENT_BINARY_DIR}/parser.cpp
+    COMPILE_FLAGS "-d")
+flex_target(scanner
+    ${CMAKE_CURRENT_SOURCE_DIR}/scanner.l
+    ${CMAKE_CURRENT_BINARY_DIR}/scanner.cpp)
+add_flex_bison_dependency(scanner parser)
+
+add_executable(compiler
+    ast.cpp ast.hpp definition.cpp
+    type_env.cpp type_env.hpp
+    env.cpp env.hpp
+    type.cpp type.hpp
+    error.cpp error.hpp
+    binop.cpp binop.hpp
+    instruction.cpp instruction.hpp
+    ${BISON_parser_OUTPUTS}
+    ${FLEX_scanner_OUTPUTS}
+    main.cpp
+)
+target_include_directories(compiler PUBLIC ${CMAKE_CURRENT_SOURCE_DIR})
+target_include_directories(compiler PUBLIC ${CMAKE_CURRENT_BINARY_DIR})
--- a/code/compiler/07/ast.cpp
+++ b/code/compiler/07/ast.cpp
@ -0,0 +1,262 @@
+#include "ast.hpp"
+#include <ostream>
+#include "error.hpp"
+
+static void print_indent(int n, std::ostream& to) {
+    while(n--) to << "  ";
+}
+
+type_ptr ast::typecheck_common(type_mgr& mgr, const type_env& env) {
+    node_type = typecheck(mgr, env);
+    return node_type;
+}
+
+void ast::resolve_common(const type_mgr& mgr) {
+    type_var* var;
+    type_ptr resolved_type = mgr.resolve(node_type, var);
+    if(var) throw type_error("ambiguously typed program");
+
+    resolve(mgr);
+    node_type = std::move(resolved_type);
+}
+
+void ast_int::print(int indent, std::ostream& to) const {
+    print_indent(indent, to);
+    to << "INT: " << value << std::endl;
+}
+
+type_ptr ast_int::typecheck(type_mgr& mgr, const type_env& env) const {
+    return type_ptr(new type_base("Int"));
+}
+
+void ast_int::resolve(const type_mgr& mgr) const {
+    
+}
+
+void ast_int::compile(const env_ptr& env, std::vector<instruction_ptr>& into) const {
+    into.push_back(instruction_ptr(new instruction_pushint(value)));
+}
+
+void ast_lid::print(int indent, std::ostream& to) const {
+    print_indent(indent, to);
+    to << "LID: " << id << std::endl;
+}
+
+type_ptr ast_lid::typecheck(type_mgr& mgr, const type_env& env) const {
+    return env.lookup(id);
+}
+
+void ast_lid::resolve(const type_mgr& mgr) const {
+
+}
+
+void ast_lid::compile(const env_ptr& env, std::vector<instruction_ptr>& into) const {
+    into.push_back(instruction_ptr(
+        env->has_variable(id) ?
+            (instruction*) new instruction_push(env->get_offset(id)) :
+            (instruction*) new instruction_pushglobal(id)));
+}
+
+void ast_uid::print(int indent, std::ostream& to) const {
+    print_indent(indent, to);
+    to << "UID: " << id << std::endl;
+}
+
+type_ptr ast_uid::typecheck(type_mgr& mgr, const type_env& env) const {
+    return env.lookup(id);
+}
+
+void ast_uid::resolve(const type_mgr& mgr) const {
+
+}
+
+void ast_uid::compile(const env_ptr& env, std::vector<instruction_ptr>& into) const {
+    into.push_back(instruction_ptr(new instruction_pushglobal(id)));
+}
+
+void ast_binop::print(int indent, std::ostream& to) const {
+    print_indent(indent, to);
+    to << "BINOP: " << op_name(op) << std::endl;
+    left->print(indent + 1, to);
+    right->print(indent + 1, to);
+}
+
+type_ptr ast_binop::typecheck(type_mgr& mgr, const type_env& env) const {
+    type_ptr ltype = left->typecheck_common(mgr, env);
+    type_ptr rtype = right->typecheck_common(mgr, env);
+    type_ptr ftype = env.lookup(op_name(op));
+    if(!ftype) throw type_error(std::string("unknown binary operator ") + op_name(op));
+
+    type_ptr return_type = mgr.new_type();
+    type_ptr arrow_one = type_ptr(new type_arr(rtype, return_type));
+    type_ptr arrow_two = type_ptr(new type_arr(ltype, arrow_one));
+
+    mgr.unify(arrow_two, ftype);
+    return return_type;
+}
+
+void ast_binop::resolve(const type_mgr& mgr) const {
+    left->resolve_common(mgr);
+    right->resolve_common(mgr);
+}
+
+void ast_binop::compile(const env_ptr& env, std::vector<instruction_ptr>& into) const {
+    right->compile(env, into);
+    left->compile(env_ptr(new env_offset(1, env)), into);
+
+    into.push_back(instruction_ptr(new instruction_pushglobal(op_action(op))));
+    into.push_back(instruction_ptr(new instruction_mkapp()));
+    into.push_back(instruction_ptr(new instruction_mkapp()));
+}
+
+void ast_app::print(int indent, std::ostream& to) const {
+    print_indent(indent, to);
+    to << "APP:" << std::endl;
+    left->print(indent + 1, to);
+    right->print(indent + 1, to);
+}
+
+type_ptr ast_app::typecheck(type_mgr& mgr, const type_env& env) const {
+    type_ptr ltype = left->typecheck_common(mgr, env);
+    type_ptr rtype = right->typecheck_common(mgr, env);
+
+    type_ptr return_type = mgr.new_type();
+    type_ptr arrow = type_ptr(new type_arr(rtype, return_type));
+    mgr.unify(arrow, ltype);
+    return return_type;
+}
+
+void ast_app::resolve(const type_mgr& mgr) const {
+    left->resolve_common(mgr);
+    right->resolve_common(mgr);
+}
+
+void ast_app::compile(const env_ptr& env, std::vector<instruction_ptr>& into) const {
+    right->compile(env, into);
+    left->compile(env_ptr(new env_offset(1, env)), into);
+    into.push_back(instruction_ptr(new instruction_mkapp()));
+}
+
+void ast_case::print(int indent, std::ostream& to) const {
+    print_indent(indent, to);
+    to << "CASE: " << std::endl;
+    for(auto& branch : branches) {
+        print_indent(indent + 1, to);
+        branch->pat->print(to);
+        to << std::endl;
+        branch->expr->print(indent + 2, to);
+    }
+}
+
+type_ptr ast_case::typecheck(type_mgr& mgr, const type_env& env) const {
+    type_var* var;
+    type_ptr case_type = mgr.resolve(of->typecheck_common(mgr, env), var);
+    type_ptr branch_type = mgr.new_type();
+
+    for(auto& branch : branches) {
+        type_env new_env = env.scope();
+        branch->pat->match(case_type, mgr, new_env);
+        type_ptr curr_branch_type = branch->expr->typecheck_common(mgr, new_env);
+        mgr.unify(branch_type, curr_branch_type);
+    }
+
+    case_type = mgr.resolve(case_type, var);
+    if(!dynamic_cast<type_data*>(case_type.get())) {
+        throw type_error("attempting case analysis of non-data type");
+    }
+
+    return branch_type;
+}
+
+void ast_case::resolve(const type_mgr& mgr) const {
+    of->resolve_common(mgr);
+    for(auto& branch : branches) {
+        branch->expr->resolve_common(mgr);
+    }
+}
+
+void ast_case::compile(const env_ptr& env, std::vector<instruction_ptr>& into) const {
+    type_data* type = dynamic_cast<type_data*>(of->node_type.get());
+
+    of->compile(env, into);
+    into.push_back(instruction_ptr(new instruction_eval()));
+
+    instruction_jump* jump_instruction = new instruction_jump();
+    into.push_back(instruction_ptr(jump_instruction));
+    for(auto& branch : branches) {
+        std::vector<instruction_ptr> branch_instructions;
+        pattern_var* vpat;
+        pattern_constr* cpat;
+
+        if((vpat = dynamic_cast<pattern_var*>(branch->pat.get()))) {
+            branch->expr->compile(env_ptr(new env_offset(1, env)), branch_instructions);
+
+            for(auto& constr_pair : type->constructors) {
+                if(jump_instruction->tag_mappings.find(constr_pair.second.tag) !=
+                        jump_instruction->tag_mappings.end())
+                    break;
+
+                jump_instruction->tag_mappings[constr_pair.second.tag] =
+                    jump_instruction->branches.size();
+            }
+            jump_instruction->branches.push_back(std::move(branch_instructions));
+        } else if((cpat = dynamic_cast<pattern_constr*>(branch->pat.get()))) {
+            env_ptr new_env = env;
+            for(auto it = cpat->params.rbegin(); it != cpat->params.rend(); it++) {
+                new_env = env_ptr(new env_var(*it, new_env));
+            }
+
+            branch_instructions.push_back(instruction_ptr(new instruction_split()));
+            branch->expr->compile(new_env, branch_instructions);
+            branch_instructions.push_back(instruction_ptr(new instruction_slide(
+                            cpat->params.size())));
+
+            int new_tag = type->constructors[cpat->constr].tag;
+            if(jump_instruction->tag_mappings.find(new_tag) !=
+                    jump_instruction->tag_mappings.end())
+                throw type_error("technically not a type error: duplicate pattern");
+
+            jump_instruction->tag_mappings[new_tag] =
+                jump_instruction->branches.size();
+            jump_instruction->branches.push_back(std::move(branch_instructions));
+        }
+    }
+
+    for(auto& constr_pair : type->constructors) {
+        if(jump_instruction->tag_mappings.find(constr_pair.second.tag) ==
+                jump_instruction->tag_mappings.end())
+            throw type_error("non-total pattern");
+    }
+}
+
+void pattern_var::print(std::ostream& to) const {
+    to << var;
+}
+
+void pattern_var::match(type_ptr t, type_mgr& mgr, type_env& env) const {
+    env.bind(var, t);
+}
+
+void pattern_constr::print(std::ostream& to) const {
+    to << constr;
+    for(auto& param : params) {
+        to << " " << param;
+    }
+}
+
+void pattern_constr::match(type_ptr t, type_mgr& mgr, type_env& env) const {
+    type_ptr constructor_type = env.lookup(constr);
+    if(!constructor_type) {
+        throw type_error(std::string("pattern using unknown constructor ") + constr);
+    }
+
+    for(int i = 0; i < params.size(); i++) {
+        type_arr* arr = dynamic_cast<type_arr*>(constructor_type.get());
+        if(!arr) throw type_error("too many parameters in constructor pattern");
+
+        env.bind(params[i], arr->left);
+        constructor_type = arr->right;
+    }
+
+    mgr.unify(t, constructor_type);
+}
--- a/code/compiler/07/ast.hpp
+++ b/code/compiler/07/ast.hpp
@ -0,0 +1,197 @@
+#pragma once
+#include <memory>
+#include <vector>
+#include "type.hpp"
+#include "type_env.hpp"
+#include "binop.hpp"
+#include "instruction.hpp"
+#include "env.hpp"
+
+struct ast {
+    type_ptr node_type;
+
+    virtual ~ast() = default;
+
+    virtual void print(int indent, std::ostream& to) const = 0;
+    virtual type_ptr typecheck(type_mgr& mgr, const type_env& env) const = 0;
+    virtual void resolve(const type_mgr& mgr) const = 0;
+    virtual void compile(const env_ptr& env,
+        std::vector<instruction_ptr>& into) const = 0;
+
+    type_ptr typecheck_common(type_mgr& mgr, const type_env& env);
+    void resolve_common(const type_mgr& mgr);
+};
+
+using ast_ptr = std::unique_ptr<ast>;
+
+struct pattern {
+    virtual ~pattern() = default;
+
+    virtual void print(std::ostream& to) const = 0;
+    virtual void match(type_ptr t, type_mgr& mgr, type_env& env) const = 0;
+};
+
+using pattern_ptr = std::unique_ptr<pattern>;
+
+struct branch {
+    pattern_ptr pat;
+    ast_ptr expr;
+
+    branch(pattern_ptr p, ast_ptr a)
+        : pat(std::move(p)), expr(std::move(a)) {}
+};
+
+using branch_ptr = std::unique_ptr<branch>;
+
+struct constructor {
+    std::string name;
+    std::vector<std::string> types;
+    int8_t tag;
+
+    constructor(std::string n, std::vector<std::string> ts)
+        : name(std::move(n)), types(std::move(ts)) {}
+};
+
+using constructor_ptr = std::unique_ptr<constructor>;
+
+struct definition {
+    virtual ~definition() = default;
+    
+    virtual void typecheck_first(type_mgr& mgr, type_env& env) = 0;
+    virtual void typecheck_second(type_mgr& mgr, const type_env& env) const = 0;
+    virtual void resolve(const type_mgr& mgr) = 0;
+    virtual void compile() = 0;
+};
+
+using definition_ptr = std::unique_ptr<definition>;
+
+struct ast_int : public ast {
+    int value;
+
+    explicit ast_int(int v)
+        : value(v) {}
+
+    void print(int indent, std::ostream& to) const;
+    type_ptr typecheck(type_mgr& mgr, const type_env& env) const;
+    void resolve(const type_mgr& mgr) const;
+    void compile(const env_ptr& env, std::vector<instruction_ptr>& into) const;
+};
+
+struct ast_lid : public ast {
+    std::string id;
+
+    explicit ast_lid(std::string i)
+        : id(std::move(i)) {}
+
+    void print(int indent, std::ostream& to) const;
+    type_ptr typecheck(type_mgr& mgr, const type_env& env) const;
+    void resolve(const type_mgr& mgr) const;
+    void compile(const env_ptr& env, std::vector<instruction_ptr>& into) const;
+};
+
+struct ast_uid : public ast {
+    std::string id;
+
+    explicit ast_uid(std::string i)
+        : id(std::move(i)) {}
+
+    void print(int indent, std::ostream& to) const;
+    type_ptr typecheck(type_mgr& mgr, const type_env& env) const;
+    void resolve(const type_mgr& mgr) const;
+    void compile(const env_ptr& env, std::vector<instruction_ptr>& into) const;
+};
+
+struct ast_binop : public ast {
+    binop op;  
+    ast_ptr left;
+    ast_ptr right;
+
+    ast_binop(binop o, ast_ptr l, ast_ptr r)
+        : op(o), left(std::move(l)), right(std::move(r)) {}
+
+    void print(int indent, std::ostream& to) const;
+    type_ptr typecheck(type_mgr& mgr, const type_env& env) const;
+    void resolve(const type_mgr& mgr) const;
+    void compile(const env_ptr& env, std::vector<instruction_ptr>& into) const;
+};
+
+struct ast_app : public ast {
+    ast_ptr left;
+    ast_ptr right;
+
+    ast_app(ast_ptr l, ast_ptr r)
+        : left(std::move(l)), right(std::move(r)) {}
+
+    void print(int indent, std::ostream& to) const;
+    type_ptr typecheck(type_mgr& mgr, const type_env& env) const;
+    void resolve(const type_mgr& mgr) const;
+    void compile(const env_ptr& env, std::vector<instruction_ptr>& into) const;
+};
+
+struct ast_case : public ast {
+    ast_ptr of;
+    std::vector<branch_ptr> branches;
+
+    ast_case(ast_ptr o, std::vector<branch_ptr> b)
+        : of(std::move(o)), branches(std::move(b)) {}
+
+    void print(int indent, std::ostream& to) const;
+    type_ptr typecheck(type_mgr& mgr, const type_env& env) const;
+    void resolve(const type_mgr& mgr) const;
+    void compile(const env_ptr& env, std::vector<instruction_ptr>& into) const;
+};
+
+struct pattern_var : public pattern {
+    std::string var;
+
+    pattern_var(std::string v)
+        : var(std::move(v)) {}
+
+    void print(std::ostream &to) const;
+    void match(type_ptr t, type_mgr& mgr, type_env& env) const;
+};
+
+struct pattern_constr : public pattern {
+    std::string constr;
+    std::vector<std::string> params;
+
+    pattern_constr(std::string c, std::vector<std::string> p)
+        : constr(std::move(c)), params(std::move(p)) {}
+
+    void print(std::ostream &to) const;
+    void match(type_ptr t, type_mgr&, type_env& env) const;
+};
+
+struct definition_defn : public definition {
+    std::string name;
+    std::vector<std::string> params;
+    ast_ptr body;
+
+    type_ptr return_type;
+    std::vector<type_ptr> param_types;
+
+    std::vector<instruction_ptr> instructions;
+
+    definition_defn(std::string n, std::vector<std::string> p, ast_ptr b)
+        : name(std::move(n)), params(std::move(p)), body(std::move(b)) {
+
+    }
+
+    void typecheck_first(type_mgr& mgr, type_env& env);
+    void typecheck_second(type_mgr& mgr, const type_env& env) const;
+    void resolve(const type_mgr& mgr);
+    void compile();
+};
+
+struct definition_data : public definition {
+    std::string name;
+    std::vector<constructor_ptr> constructors;
+
+    definition_data(std::string n, std::vector<constructor_ptr> cs)
+        : name(std::move(n)), constructors(std::move(cs)) {}
+
+    void typecheck_first(type_mgr& mgr, type_env& env);
+    void typecheck_second(type_mgr& mgr, const type_env& env) const;
+    void resolve(const type_mgr& mgr);
+    void compile();
+};
--- a/code/compiler/07/binop.cpp
+++ b/code/compiler/07/binop.cpp
@ -0,0 +1,21 @@
+#include "binop.hpp"
+
+std::string op_name(binop op) {
+    switch(op) {
+        case PLUS: return "+";
+        case MINUS: return "-";
+        case TIMES: return "*";
+        case DIVIDE: return "/";
+    }
+    return "??";
+}
+
+std::string op_action(binop op) {
+    switch(op) {
+        case PLUS: return "plus";
+        case MINUS: return "minus";
+        case TIMES: return "times";
+        case DIVIDE: return "divide";
+    }
+    return "??";
+}
--- a/code/compiler/07/binop.hpp
+++ b/code/compiler/07/binop.hpp
@ -0,0 +1,12 @@
+#pragma once
+#include <string>
+
+enum binop {
+    PLUS,
+    MINUS,
+    TIMES,
+    DIVIDE
+};
+
+std::string op_name(binop op);
+std::string op_action(binop op);
--- a/code/compiler/07/definition.cpp
+++ b/code/compiler/07/definition.cpp
@ -0,0 +1,83 @@
+#include "ast.hpp"
+#include "error.hpp"
+
+void definition_defn::typecheck_first(type_mgr& mgr, type_env& env) {
+    return_type = mgr.new_type();
+    type_ptr full_type = return_type;
+
+    for(auto it = params.rbegin(); it != params.rend(); it++) {
+        type_ptr param_type = mgr.new_type();
+        full_type = type_ptr(new type_arr(param_type, full_type));
+        param_types.push_back(param_type);
+    }
+
+    env.bind(name, full_type);
+}
+
+void definition_defn::typecheck_second(type_mgr& mgr, const type_env& env) const {
+    type_env new_env = env.scope();
+    auto param_it = params.begin();
+    auto type_it = param_types.rbegin();
+
+    while(param_it != params.end() && type_it != param_types.rend()) {
+        new_env.bind(*param_it, *type_it);
+        param_it++;
+        type_it++;
+    }
+
+    type_ptr body_type = body->typecheck_common(mgr, new_env);
+    mgr.unify(return_type, body_type);
+}
+
+void definition_defn::resolve(const type_mgr& mgr) {
+    type_var* var;
+    body->resolve_common(mgr);
+
+    return_type = mgr.resolve(return_type, var);
+    if(var) throw type_error("ambiguously typed program");
+    for(auto& param_type : param_types) {
+        param_type = mgr.resolve(param_type, var);
+        if(var) throw type_error("ambiguously typed program");
+    }
+}
+
+void definition_defn::compile() {
+    env_ptr new_env = env_ptr(new env_offset(0, nullptr));
+    for(auto it = params.rbegin(); it != params.rend(); it++) {
+        new_env = env_ptr(new env_var(*it, new_env));
+    }
+    body->compile(new_env, instructions);
+    instructions.push_back(instruction_ptr(new instruction_update(params.size())));
+    instructions.push_back(instruction_ptr(new instruction_pop(params.size())));
+}
+
+void definition_data::typecheck_first(type_mgr& mgr, type_env& env) {
+    type_data* this_type = new type_data(name);
+    type_ptr return_type = type_ptr(this_type);
+    int next_tag = 0;
+
+    for(auto& constructor : constructors) {
+        constructor->tag = next_tag;
+        this_type->constructors[constructor->name] = { next_tag++ };
+
+        type_ptr full_type = return_type;
+        for(auto it = constructor->types.rbegin(); it != constructor->types.rend(); it++) {
+            type_ptr type = type_ptr(new type_base(*it));
+            full_type = type_ptr(new type_arr(type, full_type));
+        }
+
+        env.bind(constructor->name, full_type);
+    }
+}
+
+void definition_data::typecheck_second(type_mgr& mgr, const type_env& env) const {
+    // Nothing
+}
+
+void definition_data::resolve(const type_mgr& mgr) {
+    // Nothing
+}
+
+void definition_data::compile() {
+
+}
--- a/code/compiler/07/env.cpp
+++ b/code/compiler/07/env.cpp
@ -0,0 +1,23 @@
+#include "env.hpp"
+
+int env_var::get_offset(const std::string& name) const {
+    if(name == this->name) return 0;
+    if(parent) return parent->get_offset(name) + 1;
+    throw 0;
+}
+
+bool env_var::has_variable(const std::string& name) const {
+    if(name == this->name) return true;
+    if(parent) return parent->has_variable(name);
+    return false;
+}
+
+int env_offset::get_offset(const std::string& name) const {
+    if(parent) return parent->get_offset(name) + offset;
+    throw 0;
+}
+
+bool env_offset::has_variable(const std::string& name) const {
+    if(parent) return parent->has_variable(name);
+    return false;
+}
--- a/code/compiler/07/env.hpp
+++ b/code/compiler/07/env.hpp
@ -0,0 +1,34 @@
+#pragma once
+#include <memory>
+#include <string>
+
+struct env {
+    virtual ~env() = default;
+
+    virtual int get_offset(const std::string& name) const = 0;
+    virtual bool has_variable(const std::string& name) const = 0;
+};
+
+using env_ptr = std::shared_ptr<env>;
+
+struct env_var : public env {
+    std::string name;
+    env_ptr parent;
+
+    env_var(std::string& n, env_ptr p)
+        : name(std::move(n)), parent(std::move(p)) {}
+
+    int get_offset(const std::string& name) const;
+    bool has_variable(const std::string& name) const;
+};
+
+struct env_offset : public env {
+    int offset;
+    env_ptr parent;
+
+    env_offset(int o, env_ptr p)
+        : offset(o), parent(std::move(p)) {}
+
+    int get_offset(const std::string& name) const;
+    bool has_variable(const std::string& name) const;
+};
--- a/code/compiler/07/error.cpp
+++ b/code/compiler/07/error.cpp
@ -0,0 +1,5 @@
+#include "error.hpp"
+
+const char* type_error::what() const noexcept {
+    return "an error occured while checking the types of the program";
+}
--- a/code/compiler/07/error.hpp
+++ b/code/compiler/07/error.hpp
@ -0,0 +1,21 @@
+#pragma once
+#include <exception>
+#include "type.hpp"
+
+struct type_error : std::exception {
+    std::string description;
+
+    type_error(std::string d)
+        : description(std::move(d)) {}
+
+    const char* what() const noexcept override;
+};
+
+struct unification_error : public type_error {
+    type_ptr left;
+    type_ptr right;
+
+    unification_error(type_ptr l, type_ptr r)
+        : left(std::move(l)), right(std::move(r)), 
+            type_error("failed to unify types") {}
+};
--- a/code/compiler/07/examples/bad1.txt
+++ b/code/compiler/07/examples/bad1.txt
@ -0,0 +1,2 @@
+data Bool = { True, False }
+defn main = { 3 + True }
--- a/code/compiler/07/examples/bad2.txt
+++ b/code/compiler/07/examples/bad2.txt
@ -0,0 +1 @@
+defn main = { 1 2 3 4 5 }
--- a/code/compiler/07/examples/bad3.txt
+++ b/code/compiler/07/examples/bad3.txt
@ -0,0 +1,8 @@
+data List = { Nil, Cons Int List }
+
+defn head l = {
+    case l of {
+        Nil -> { 0 }
+        Cons x y z -> { x }
+    }
+}
--- a/code/compiler/07/examples/runtime1.c
+++ b/code/compiler/07/examples/runtime1.c
@ -0,0 +1,31 @@
+#include "../runtime.h"
+
+void f_add(struct stack* s) {
+    struct node_num* left = (struct node_num*) eval(stack_peek(s, 0));
+    struct node_num* right = (struct node_num*) eval(stack_peek(s, 1));
+    stack_push(s, (struct node_base*) alloc_num(left->value + right->value));
+}
+
+void f_main(struct stack* s) {
+    // PushInt 320
+    stack_push(s, (struct node_base*) alloc_num(320));
+
+    // PushInt 6
+    stack_push(s, (struct node_base*) alloc_num(6));
+
+    // PushGlobal f_add (the function for +)
+    stack_push(s, (struct node_base*) alloc_global(f_add, 2));
+
+    struct node_base* left;
+    struct node_base* right;
+    
+    // MkApp
+    left = stack_pop(s);
+    right = stack_pop(s);
+    stack_push(s, (struct node_base*) alloc_app(left, right));
+    
+    // MkApp
+    left = stack_pop(s);
+    right = stack_pop(s);
+    stack_push(s, (struct node_base*) alloc_app(left, right));
+}
--- a/code/compiler/07/examples/works1.txt
+++ b/code/compiler/07/examples/works1.txt
@ -0,0 +1,2 @@
+defn main = { plus 320 6 }
+defn plus x y = { x + y }
--- a/code/compiler/07/examples/works2.txt
+++ b/code/compiler/07/examples/works2.txt
@ -0,0 +1,3 @@
+defn add x y = { x + y }
+defn double x = { add x x }
+defn main = { double 163 }
--- a/Show More
+++ b/Show More
Author	SHA1	Message	Date
Danila Fedorin	0b5748cc5a	Add links in part 0 of compiler series.	2020-09-07 00:21:01 -07:00
Danila Fedorin	cd574b43fd	Finalize draft of compilers part 0.	2020-09-02 16:56:37 -07:00
Danila Fedorin	8466a5601e	Add a draft of a big portion of the translation of the 0th compilers post.	2020-08-29 17:17:43 -07:00
Danila Fedorin	845d1ae7d8	Add russian index.	2020-08-20 18:35:50 -07:00
Danila Fedorin	988bf72786	Enable localization for Russian.	2020-08-20 18:33:55 -07:00
Danila Fedorin	8557dc4399	Replace more hardcoded strings with their i18nized versions.	2020-08-12 19:15:14 -07:00
Danila Fedorin	7d1fcdb0c5	Add rough russian translation.	2020-08-12 19:07:54 -07:00
Danila Fedorin	bda78fed78	Use localization files in templates.	2020-08-12 17:41:47 -07:00
				`@ -1 +0,0 @@`
				`Subproject commit 828b652d3b9266e27ef7cf5a8a7fb82e3fd3133f`
				`@ -1 +0,0 @@`
				`Subproject commit 7a8503c3fe1aa7e624e4d8672aa9b56d24b4ba82`
				`@ -1 +0,0 @@`
				`Subproject commit 67b47d9c298e7476c2ca211aac5c5fd961637b7b`
				`@ -1 +0,0 @@`
				`Subproject commit 137455b0f4365ba3fd11c45ce49781cdbe829ec3`
				`@ -0,0 +1 @@`
				`rm -f parser.o parser.cpp parser.hpp stack.hh scanner.cpp scanner.o a.out`