diff --git a/code/compiler/08/ast.hpp b/code/compiler/08/ast.hpp
index c536d17..c88fc99 100644
--- a/code/compiler/08/ast.hpp
+++ b/code/compiler/08/ast.hpp
@@ -43,27 +43,6 @@ struct branch {
 
 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;
-    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;
 
@@ -160,37 +139,3 @@ struct pattern_constr : public pattern {
     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();
-};
diff --git a/code/compiler/08/definition.cpp b/code/compiler/08/definition.cpp
index 34c6f66..b3fb4df 100644
--- a/code/compiler/08/definition.cpp
+++ b/code/compiler/08/definition.cpp
@@ -1,5 +1,6 @@
-#include "ast.hpp"
+#include "definition.hpp"
 #include "error.hpp"
+#include "ast.hpp"
 
 void definition_defn::typecheck_first(type_mgr& mgr, type_env& env) {
     return_type = mgr.new_type();
diff --git a/code/compiler/08/definition.hpp b/code/compiler/08/definition.hpp
new file mode 100644
index 0000000..1431b8b
--- /dev/null
+++ b/code/compiler/08/definition.hpp
@@ -0,0 +1,63 @@
+#pragma once
+#include <memory>
+#include <vector>
+#include "instruction.hpp"
+#include "type_env.hpp"
+
+struct ast;
+using ast_ptr = std::unique_ptr<ast>;
+
+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 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_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();
+};
diff --git a/code/compiler/08/main.cpp b/code/compiler/08/main.cpp
index ffbd4e5..728e2a6 100644
--- a/code/compiler/08/main.cpp
+++ b/code/compiler/08/main.cpp
@@ -1,5 +1,6 @@
 #include "ast.hpp"
 #include <iostream>
+#include "definition.hpp"
 #include "parser.hpp"
 #include "error.hpp"
 #include "type.hpp"
diff --git a/code/compiler/08/parser.y b/code/compiler/08/parser.y
index 3874aca..088648d 100644
--- a/code/compiler/08/parser.y
+++ b/code/compiler/08/parser.y
@@ -2,6 +2,7 @@
 #include <string>
 #include <iostream>
 #include "ast.hpp"
+#include "definition.hpp"
 #include "parser.hpp"
 
 std::vector<definition_ptr> program;
diff --git a/code/compiler/08/scanner.l b/code/compiler/08/scanner.l
index 683deeb..c8a4429 100644
--- a/code/compiler/08/scanner.l
+++ b/code/compiler/08/scanner.l
@@ -3,6 +3,7 @@
 %{
 #include <iostream>
 #include "ast.hpp"
+#include "definition.hpp"
 #include "parser.hpp"
 
 #define YY_DECL yy::parser::symbol_type yylex()