diff --git a/12/ast.cpp b/12/ast.cpp
index 5bdd00c..e6d8cbb 100644
--- a/12/ast.cpp
+++ b/12/ast.cpp
@@ -226,6 +226,32 @@ void ast_case::compile(const env_ptr& env, std::vector<instruction_ptr>& into) c
     }
 }
 
+void ast_let::print(int indent, std::ostream& to) const {
+    print_indent(indent, to);
+    to << "LET: " << std::endl;
+    in->print(indent + 1, to);
+}
+
+void ast_let::find_free(type_mgr& mgr, type_env_ptr& env, std::set<std::string>& into) {
+    this->env = env;
+    definitions.find_free(mgr, env, into);
+    std::set<std::string> all_free;
+    in->find_free(mgr, definitions.env, all_free);
+    for(auto& free_var : all_free) {
+        if(definitions.defs_defn.find(free_var) == definitions.defs_defn.end())
+            into.insert(free_var);
+    }
+}
+
+type_ptr ast_let::typecheck(type_mgr& mgr) {
+    definitions.typecheck(mgr);
+    return in->typecheck(mgr);
+}
+
+void ast_let::compile(const env_ptr& env, std::vector<instruction_ptr>& into) const {
+    throw 0;
+}
+
 void pattern_var::print(std::ostream& to) const {
     to << var;
 }
diff --git a/12/ast.hpp b/12/ast.hpp
index 6c66636..68082ab 100644
--- a/12/ast.hpp
+++ b/12/ast.hpp
@@ -7,6 +7,7 @@
 #include "binop.hpp"
 #include "instruction.hpp"
 #include "env.hpp"
+#include "definition.hpp"
 
 struct ast {
     type_env_ptr env;
@@ -120,6 +121,19 @@ struct ast_case : public ast {
     void compile(const env_ptr& env, std::vector<instruction_ptr>& into) const;
 };
 
+struct ast_let : public ast {
+    definition_group definitions;
+    ast_ptr in;
+
+    ast_let(ast_ptr i, definition_group g)
+        : in(std::move(i)), definitions(std::move(g)) {}
+
+    void print(int indent, std::ostream& to) const;
+    void find_free(type_mgr& mgr, type_env_ptr& env, std::set<std::string>& into);
+    type_ptr typecheck(type_mgr& mgr);
+    void compile(const env_ptr& env, std::vector<instruction_ptr>& into) const;
+};
+
 struct pattern_var : public pattern {
     std::string var;