diff --git a/bin/tests/sicp.slime b/bin/tests/sicp.slime
index 8b393f7..7a469a3 100644
--- a/bin/tests/sicp.slime
+++ b/bin/tests/sicp.slime
@@ -338,3 +338,4 @@
 (define (close-enough? x y) (< (abs (- x y)) 0.001))
 
 (assert (close-enough? (search (lambda (x) (- 1 (square x))) -3 3) -1))
+
diff --git a/bin/visualization.svg b/bin/visualization.svg
index 87bb694..66b1de7 100644
--- a/bin/visualization.svg
+++ b/bin/visualization.svg
@@ -16,7 +16,7 @@
    Time: 
   </text>
   <text x='304' y='24' font-size='20' font-family='monospace' style='fill: #000000'>
-   11:40:20
+   16:44:55
   </text>
   <text x='420' y='24' font-size='20' font-family='monospace' style='fill: #000000'>
    |
diff --git a/src/built_ins.cpp b/src/built_ins.cpp
index 7fecaf2..be69c0c 100644
--- a/src/built_ins.cpp
+++ b/src/built_ins.cpp
@@ -17,7 +17,7 @@ proc lisp_object_equal(Lisp_Object* n1, Lisp_Object* n2) -> bool {
                                    // unnecessary once symbols and
                                    // keywords are memory unique
     case Lisp_Object_Type::Keyword:
-        return string_equal(n1->value.identifier, n2->value.identifier);
+        return string_equal(n1->value.symbol.identifier, n2->value.symbol.identifier);
     case Lisp_Object_Type::Number: return n1->value.number == n2->value.number;
     case Lisp_Object_Type::String: return string_equal(n1->value.string, n2->value.string);
     case Lisp_Object_Type::Pair:
@@ -440,7 +440,7 @@ proc load_built_ins_into_environment(Environment* env) -> void {
                 // it is a pair!
                 Lisp_Object* originalPair = expr->value.pair.first;
                 if (Memory::get_type(originalPair) == Lisp_Object_Type::Symbol &&
-                    string_equal(originalPair->value.identifier, "unquote"))
+                    string_equal(originalPair->value.symbol.identifier, "unquote"))
                 {
                     // eval replace the stuff
                     return eval_expr(expr->value.pair.rest->value.pair.first, env);
@@ -740,9 +740,9 @@ proc load_built_ins_into_environment(Environment* env) -> void {
 
                 // TODO(Felix): Maybe don't compare strings here?? Wtf
                 if (Memory::get_type(type) == Lisp_Object_Type::Keyword &&
-                    (string_equal(type->value.identifier, "lambda") ||
-                     string_equal(type->value.identifier, "special-lambda") ||
-                     string_equal(type->value.identifier, "macro")))
+                    (string_equal(type->value.symbol.identifier, "lambda") ||
+                     string_equal(type->value.symbol.identifier, "special-lambda") ||
+                     string_equal(type->value.symbol.identifier, "macro")))
                 {
                     Lisp_Object* fun = eval_expr(arguments->value.pair.first, env);
 
@@ -926,7 +926,7 @@ proc load_built_ins_into_environment(Environment* env) -> void {
 
             Lisp_Object* source = evaluated_arguments->value.pair.first;
 
-            return Memory::get_or_create_lisp_object_keyword(source->value.identifier);
+            return Memory::get_or_create_lisp_object_keyword(source->value.symbol.identifier);
         });
     defun("string->symbol", cLambda {
             // TODO(Felix): do some sanity checks on the string. For
@@ -947,7 +947,7 @@ proc load_built_ins_into_environment(Environment* env) -> void {
 
             Lisp_Object* source = evaluated_arguments->value.pair.first;
 
-            return Memory::create_lisp_object_string(Memory::duplicate_string(source->value.identifier));
+            return Memory::create_lisp_object_string(Memory::duplicate_string(source->value.symbol.identifier));
         });
     defun("concat-strings", cLambda {
             try evaluated_arguments = eval_arguments(arguments, env, &arguments_length);
diff --git a/src/env.cpp b/src/env.cpp
index e927f1c..68bcbbc 100644
--- a/src/env.cpp
+++ b/src/env.cpp
@@ -10,7 +10,7 @@ proc define_symbol(Lisp_Object* symbol, Lisp_Object* value, Environment* env) ->
         env->values = (Lisp_Object**)realloc(env->values, env->capacity * sizeof(Lisp_Object*));
     }
 
-    env->keys  [env->next_index] = Memory::get_c_str(symbol->value.identifier);
+    env->keys  [env->next_index] = Memory::get_c_str(symbol->value.symbol.identifier);
     env->values[env->next_index] = value;
     ++env->next_index;
 }
@@ -24,7 +24,7 @@ proc lookup_symbol_in_this_envt(String* identifier, Environment* env) -> Lisp_Ob
 
 proc try_lookup_symbol(Lisp_Object* node, Environment* env) -> Lisp_Object* {
     // first check current environment
-    String* identifier = node->value.identifier;
+    String* identifier = node->value.symbol.identifier;
     Lisp_Object* result;
     result = lookup_symbol_in_this_envt(identifier, env);
     if (result)
@@ -53,7 +53,7 @@ proc lookup_symbol(Lisp_Object* node, Environment* env) -> Lisp_Object* {
     if (result)
         return result;
 
-    String* identifier = node->value.identifier;
+    String* identifier = node->value.symbol.identifier;
     create_symbol_undefined_error("The symbol '%s' is not defined.", &identifier->data);
     print_environment(env);
     return nullptr;
diff --git a/src/error.cpp b/src/error.cpp
index df7155c..2fef0ba 100644
--- a/src/error.cpp
+++ b/src/error.cpp
@@ -14,7 +14,7 @@ proc create_error(const char* c_file_name, int c_file_line, Lisp_Object* type, S
     delete_error();
     debug_break();
 
-    // visualize_lisp_machine();
+    visualize_lisp_machine();
 
     using Globals::error;
     error = new(Error);
diff --git a/src/eval.cpp b/src/eval.cpp
index 26bcb86..fcbfdac 100644
--- a/src/eval.cpp
+++ b/src/eval.cpp
@@ -34,7 +34,7 @@ proc apply_arguments_to_function(Lisp_Object* arguments, Function* function) ->
         bool accepted = false;
         for (int i = 0; i < function->keyword_arguments->next_index; ++i) {
             if (string_equal(
-                    arguments->value.pair.first->value.identifier,
+                    arguments->value.pair.first->value.symbol.identifier,
                     function->keyword_arguments->identifiers[i]))
             {
                 accepted = true;
@@ -48,14 +48,14 @@ proc apply_arguments_to_function(Lisp_Object* arguments, Function* function) ->
             // (special case with default variables)
             create_generic_error(
                 "The function does not take the keyword argument ':%s'",
-                &(arguments->value.pair.first->value.identifier));
+                &(arguments->value.pair.first->value.symbol.identifier));
             return nullptr;
         }
 
         // check if it was already read in
         for (int i = 0; i < read_in_keywords->next_index; ++i) {
             if (string_equal(
-                    arguments->value.pair.first->value.identifier,
+                    arguments->value.pair.first->value.symbol.identifier,
                     read_in_keywords->data[i]))
             {
                 // TODO(Felix): if we are actually done with all the
@@ -64,7 +64,7 @@ proc apply_arguments_to_function(Lisp_Object* arguments, Function* function) ->
                 // (special case with default variables)
                 create_generic_error(
                     "The function already read the keyword argument ':%s'",
-                    &(arguments->value.pair.first->value.identifier));
+                    &(arguments->value.pair.first->value.symbol.identifier));
                 return nullptr;
             }
         }
@@ -75,15 +75,15 @@ proc apply_arguments_to_function(Lisp_Object* arguments, Function* function) ->
         if (Memory::get_type(arguments->value.pair.rest) != Lisp_Object_Type::Pair) {
             create_generic_error(
                 "Attempting to set the keyword argument ':%s', but no value was supplied.",
-                &(arguments->value.pair.first->value.identifier));
+                &(arguments->value.pair.first->value.symbol.identifier));
             return nullptr;
         }
 
         // if not set it and then add it to the array list
-        try sym = Memory::get_or_create_lisp_object_symbol(arguments->value.pair.first->value.identifier),
+        try sym = Memory::get_or_create_lisp_object_symbol(arguments->value.pair.first->value.symbol.identifier),
         define_symbol(sym, arguments->value.pair.rest->value.pair.first, new_env);
 
-        append_to_array_list(read_in_keywords, arguments->value.pair.first->value.identifier);
+        append_to_array_list(read_in_keywords, arguments->value.pair.first->value.symbol.identifier);
 
         // overstep both for next one
         arguments = arguments->value.pair.rest->value.pair.rest;
@@ -177,13 +177,13 @@ proc parse_argument_list(Lisp_Object* arguments, Function* function) -> void {
     // okay let's try to read some positional arguments
     while (Memory::get_type(arguments) == Lisp_Object_Type::Pair) {
         if (Memory::get_type(arguments->value.pair.first) == Lisp_Object_Type::Keyword) {
-            if (string_equal(arguments->value.pair.first->value.identifier, "keys") ||
-                string_equal(arguments->value.pair.first->value.identifier, "rest"))
+            if (string_equal(arguments->value.pair.first->value.symbol.identifier, "keys") ||
+                string_equal(arguments->value.pair.first->value.symbol.identifier, "rest"))
                 break;
             else {
                 create_parsing_error("A non recognized marker was found "
                                      "in the lambda list: ':%s'",
-                                     &arguments->value.pair.first->value.identifier);
+                                     &arguments->value.pair.first->value.symbol.identifier);
                 return;
             }
         }
@@ -198,7 +198,7 @@ proc parse_argument_list(Lisp_Object* arguments, Function* function) -> void {
         // okay wow we found an actual symbol
         append_to_positional_argument_list(
             function->positional_arguments,
-            arguments->value.pair.first->value.identifier);
+            arguments->value.pair.first->value.symbol.identifier);
 
         arguments = arguments->value.pair.rest;
     }
@@ -212,7 +212,7 @@ proc parse_argument_list(Lisp_Object* arguments, Function* function) -> void {
     }
 
     if (Memory::get_type(arguments->value.pair.first) == Lisp_Object_Type::Keyword &&
-        string_equal(arguments->value.pair.first->value.identifier, "keys"))
+        string_equal(arguments->value.pair.first->value.symbol.identifier, "keys"))
     {
         arguments = arguments->value.pair.rest;
         if (Memory::get_type(arguments) != Lisp_Object_Type::Pair) {
@@ -227,12 +227,12 @@ proc parse_argument_list(Lisp_Object* arguments, Function* function) -> void {
 
         while (Memory::get_type(arguments) == Lisp_Object_Type::Pair) {
             if (Memory::get_type(arguments->value.pair.first) == Lisp_Object_Type::Keyword) {
-                if (string_equal(arguments->value.pair.first->value.identifier, "rest"))
+                if (string_equal(arguments->value.pair.first->value.symbol.identifier, "rest"))
                     break;
                 else {
                     create_parsing_error(
                         "Only the :rest keyword can be parsed here, but got ':%s'.",
-                        &arguments->value.pair.first->value.identifier->data);
+                        &arguments->value.pair.first->value.symbol.identifier->data);
                     return;
                 }
             }
@@ -250,7 +250,7 @@ proc parse_argument_list(Lisp_Object* arguments, Function* function) -> void {
             Lisp_Object* next = arguments->value.pair.rest;
             if (Memory::get_type(next) == Lisp_Object_Type::Pair &&
                 Memory::get_type(next->value.pair.first) == Lisp_Object_Type::Keyword &&
-                string_equal(next->value.pair.first->value.identifier,
+                string_equal(next->value.pair.first->value.symbol.identifier,
                               "defaults-to"))
             {
                 // check if there is a next argument too, otherwise it
@@ -258,7 +258,7 @@ proc parse_argument_list(Lisp_Object* arguments, Function* function) -> void {
                 next = next->value.pair.rest;
                 if (Memory::get_type(next) == Lisp_Object_Type::Pair) {
                     append_to_keyword_argument_list(function->keyword_arguments,
-                                                    arguments->value.pair.first->value.identifier,
+                                                    arguments->value.pair.first->value.symbol.identifier,
                                                     next->value.pair.first);
                     arguments = next->value.pair.rest;
                 } else {
@@ -268,7 +268,7 @@ proc parse_argument_list(Lisp_Object* arguments, Function* function) -> void {
             } else {
                 // No :defaults-to, so just add it to the list
                 append_to_keyword_argument_list(function->keyword_arguments,
-                                                arguments->value.pair.first->value.identifier,
+                                                arguments->value.pair.first->value.symbol.identifier,
                                                 nullptr);
                 arguments = next;
             }
@@ -285,7 +285,7 @@ proc parse_argument_list(Lisp_Object* arguments, Function* function) -> void {
     }
 
     if (Memory::get_type(arguments->value.pair.first) == Lisp_Object_Type::Keyword &&
-        string_equal(arguments->value.pair.first->value.identifier, "rest"))
+        string_equal(arguments->value.pair.first->value.symbol.identifier, "rest"))
     {
         arguments = arguments->value.pair.rest;
         if (// arguments->type != Lisp_Object_Type::Pair ||
@@ -294,7 +294,7 @@ proc parse_argument_list(Lisp_Object* arguments, Function* function) -> void {
             create_parsing_error("After the 'rest' marker there must follow a symbol.");
             return;
         }
-        function->rest_argument = arguments->value.pair.first->value.identifier;
+        function->rest_argument = arguments->value.pair.first->value.symbol.identifier;
         if (arguments->value.pair.rest != Memory::nil) {
             create_parsing_error("The lambda list must end after the rest symbol");
         }
@@ -326,7 +326,7 @@ proc list_length(Lisp_Object* node) -> int {
 proc extract_keyword_value(char* keyword, Parsed_Arguments* args) -> Lisp_Object* {
     // NOTE(Felix): This will be a hashmap lookup later
     for (int i = 0; i < args->keyword_keys->next_index; ++i) {
-        if (string_equal(args->keyword_keys->data[i]->value.identifier, keyword))
+        if (string_equal(args->keyword_keys->data[i]->value.symbol.identifier, keyword))
             return args->keyword_values->data[i];
     }
     return nullptr;
diff --git a/src/io.cpp b/src/io.cpp
index 37270f8..0a90320 100644
--- a/src/io.cpp
+++ b/src/io.cpp
@@ -211,7 +211,7 @@ proc read_line() -> char* {
     return linep;
 }
 
-proc log_message(Log_Level type, char* message) -> void {
+proc log_message(Log_Level type, const char* message) -> void {
     if (type > Globals::log_level)
         return;
 
@@ -238,7 +238,7 @@ proc print(Lisp_Object* node, bool print_quotes = false, FILE* file = stdout) ->
     case (Lisp_Object_Type::T):         fputs("t",  file);                                         break;
     case (Lisp_Object_Type::Number):    fprintf(file, "%f", node->value.number);                   break;
     case (Lisp_Object_Type::Keyword):   fputs(":", file); // NOTE(Felix): intentionall fallthough
-    case (Lisp_Object_Type::Symbol):    fprintf(file, "%s", Memory::get_c_str(node->value.identifier)); break;
+    case (Lisp_Object_Type::Symbol):    fprintf(file, "%s", Memory::get_c_str(node->value.symbol.identifier)); break;
     case (Lisp_Object_Type::CFunction): fputs("[C-function]", file);                               break;
     case (Lisp_Object_Type::String): {
         if (print_quotes) {
diff --git a/src/memory.cpp b/src/memory.cpp
index f3e6c33..cd4dbfd 100644
--- a/src/memory.cpp
+++ b/src/memory.cpp
@@ -72,6 +72,19 @@ namespace Memory {
         node->flags = (u64)(node->flags) | bitmask;
     }
 
+    proc hash(String* str) -> u64 {
+        // TODO(Felix): When parsing symbols or keywords, compute the
+        // hash while reading them in.
+        u64 value = str->data << 7;
+        for (int i = 1; i < str->length; ++i) {
+            char c = ((char*)&str->data)[i];
+            value = (1000003 * value) ^ c;
+        }
+        value ^= str->length;
+
+        return value;
+
+    }
 
     proc create_string(const char* str, int len) -> String* {
         // TODO(Felix): check the holes first, not just always append
@@ -216,7 +229,8 @@ namespace Memory {
         try node = create_lisp_object();
         set_type(node, Lisp_Object_Type::Symbol);
         // node->value.symbol = new(Symbol);
-        node->value.identifier = identifier;
+        node->value.symbol.identifier = identifier;
+        node->value.symbol.hash = hash(identifier);
         return node;
     }
 
@@ -235,7 +249,8 @@ namespace Memory {
         try node = create_lisp_object();
         set_type(node, Lisp_Object_Type::Keyword);
         // node->value.keyword = new(Keyword);
-        node->value.identifier = keyword;
+        node->value.symbol.identifier = keyword;
+        node->value.symbol.hash = hash(keyword);
         return node;
     }
 
diff --git a/src/parse.cpp b/src/parse.cpp
index fc801f8..f43ad4c 100644
--- a/src/parse.cpp
+++ b/src/parse.cpp
@@ -365,7 +365,7 @@ namespace Parser {
         // check if we have to create or delete or run macros
         while (Memory::get_type(expression->value.pair.first) == Lisp_Object_Type::Symbol) {
             Lisp_Object* parsed_symbol = expression->value.pair.first;
-            if (string_equal("define-syntax", parsed_symbol->value.identifier)) {
+            if (string_equal("define-syntax", parsed_symbol->value.symbol.identifier)) {
                 // create a new macro
                 Lisp_Object* arguments = expression->value.pair.rest;
                 Lisp_Object* body;
@@ -426,7 +426,7 @@ namespace Parser {
                 // print_environment(environment_for_macros);
                 return Memory::nil;
 
-            } else if (string_equal("delete-syntax", parsed_symbol->value.identifier)) {
+            } else if (string_equal("delete-syntax", parsed_symbol->value.symbol.identifier)) {
                 /* --- deleting an existing macro --- */
                 // TODO(Felix): this is a hard one because when
                 // environments will be made from hashmaps, how can we
diff --git a/src/structs.cpp b/src/structs.cpp
index 93a93ed..4c63548 100644
--- a/src/structs.cpp
+++ b/src/structs.cpp
@@ -57,10 +57,12 @@ struct Source_Code_Location {
 
 struct Symbol {
     String* identifier;
+    u64 hash;
 };
 
 struct Keyword {
     String* identifier;
+    u64 hash;
 };
 
 // struct Number {
@@ -109,7 +111,7 @@ struct Lisp_Object {
     u64 flags;
     Lisp_Object* userType;
     union {
-        String*   identifier; // used for symbols and keywords
+        Symbol    symbol; // used for symbols and keywords
         double    number;
         String*   string;
         Pair      pair;
diff --git a/src/testing.cpp b/src/testing.cpp
index 8c9c176..768304d 100644
--- a/src/testing.cpp
+++ b/src/testing.cpp
@@ -222,7 +222,7 @@ proc test_eval_operands() -> testresult {
 
     assert_equal_type(operands, Lisp_Object_Type::Pair);
     assert_equal_type(operands->value.pair.first, Lisp_Object_Type::Keyword);
-    assert_equal_string(operands->value.pair.first->value.identifier, "haha");
+    assert_equal_string(operands->value.pair.first->value.symbol.identifier, "haha");
 
     return pass;
 }
@@ -259,26 +259,26 @@ proc test_parse_atom() -> testresult {
 
     result = Parser::parse_atom(string, &index_in_text);
     assert_equal_type(result, Lisp_Object_Type::Keyword);
-    assert_equal_string(result->value.identifier, "key1");
+    assert_equal_string(result->value.symbol.identifier, "key1");
 
     ++index_in_text;
 
     result = Parser::parse_atom(string, &index_in_text);
     assert_equal_type(result, Lisp_Object_Type::Keyword);
-    assert_equal_string(result->value.identifier, "key:2");
+    assert_equal_string(result->value.symbol.identifier, "key:2");
 
     // test symbols
     ++index_in_text;
 
     result = Parser::parse_atom(string, &index_in_text);
     assert_equal_type(result, Lisp_Object_Type::Symbol);
-    assert_equal_string(result->value.identifier, "sym");
+    assert_equal_string(result->value.symbol.identifier, "sym");
 
     ++index_in_text;
 
     result = Parser::parse_atom(string, &index_in_text);
     assert_equal_type(result, Lisp_Object_Type::Symbol);
-    assert_equal_string(result->value.identifier, "+");
+    assert_equal_string(result->value.symbol.identifier, "+");
 
     return pass;
 }
@@ -292,13 +292,13 @@ proc test_parse_expression() -> testresult {
 
     assert_equal_type(result, Lisp_Object_Type::Pair);
     assert_equal_type(result->value.pair.first, Lisp_Object_Type::Symbol);
-    assert_equal_string(result->value.pair.first->value.identifier, "fun");
+    assert_equal_string(result->value.pair.first->value.symbol.identifier, "fun");
 
     result = result->value.pair.rest;
 
     assert_equal_type(result, Lisp_Object_Type::Pair);
     assert_equal_type(result->value.pair.first, Lisp_Object_Type::Symbol);
-    assert_equal_string(result->value.pair.first->value.identifier, "+");
+    assert_equal_string(result->value.pair.first->value.symbol.identifier, "+");
 
     result = result->value.pair.rest;
 
@@ -318,20 +318,20 @@ proc test_parse_expression() -> testresult {
 
     assert_equal_type(result, Lisp_Object_Type::Pair);
     assert_equal_type(result->value.pair.first, Lisp_Object_Type::Symbol);
-    assert_equal_string(result->value.pair.first->value.identifier, "define");
+    assert_equal_string(result->value.pair.first->value.symbol.identifier, "define");
 
     result = result->value.pair.rest;
 
     assert_equal_type(result, Lisp_Object_Type::Pair);
     assert_equal_type(result->value.pair.first, Lisp_Object_Type::Symbol);
-    assert_equal_string(result->value.pair.first->value.identifier, "fun");
+    assert_equal_string(result->value.pair.first->value.symbol.identifier, "fun");
 
     result = result->value.pair.rest;
 
     assert_equal_type(result, Lisp_Object_Type::Pair);
     assert_equal_type(result->value.pair.first, Lisp_Object_Type::Pair);
     assert_equal_type(result->value.pair.first->value.pair.first, Lisp_Object_Type::Symbol);
-    assert_equal_string(result->value.pair.first->value.pair.first->value.identifier, "lambda");
+    assert_equal_string(result->value.pair.first->value.pair.first->value.symbol.identifier, "lambda");
 
     result = result->value.pair.rest;
 
@@ -500,7 +500,7 @@ proc test_built_in_type() -> testresult {
     assert_no_error();
     assert_not_null(result);
     assert_equal_type(result, Lisp_Object_Type::Keyword);
-    assert_equal_string(result->value.identifier, "number");
+    assert_equal_string(result->value.symbol.identifier, "number");
 
     // setting user type
     char exp_string2[] = "(prog (set-type a :my-type)(type a))";
@@ -510,7 +510,7 @@ proc test_built_in_type() -> testresult {
     assert_no_error();
     assert_not_null(result);
     assert_equal_type(result, Lisp_Object_Type::Keyword);
-    assert_equal_string(result->value.identifier, "my-type");
+    assert_equal_string(result->value.symbol.identifier, "my-type");
 
     // trying to set invalid user type
     char exp_string3[] = "(prog (set-type a \"wrong tpye\")(type a))";
@@ -531,7 +531,7 @@ proc test_built_in_type() -> testresult {
     assert_no_error();
     assert_not_null(result);
     assert_equal_type(result, Lisp_Object_Type::Keyword);
-    assert_equal_string(result->value.identifier, "number");
+    assert_equal_string(result->value.symbol.identifier, "number");
 
     return pass;
 }
diff --git a/src/visualization.cpp b/src/visualization.cpp
index ec57b31..28a411f 100644
--- a/src/visualization.cpp
+++ b/src/visualization.cpp
@@ -6,9 +6,10 @@ proc visualize_lisp_machine() -> void {
         int height;
     };
 
-    fprintf(stderr, "Drawing visualization...");
+    log_message(Log_Level::Info, "Drawing visualization...");
+
     defer {
-        fprintf(stderr, "Done!\n");
+        log_message(Log_Level::Info, "Done drawing visualization!");
     };
 
     const int padding = 40;
@@ -20,15 +21,14 @@ proc visualize_lisp_machine() -> void {
 
 
     FILE *f = fopen("visualization.svg", "w");
-    defer {
-        fclose(f);
-    };
-
-    if (f == NULL) {
-        create_generic_error("The file for writing the visualization"
+    if (!f) {
+        create_generic_error("The file for writing the visualization "
                              "could not be opened for writing");
         return;
     }
+    defer {
+        fclose(f);
+    };
 
     int max_x   = 0,
         max_y   = 0,
@@ -170,7 +170,7 @@ proc visualize_lisp_machine() -> void {
         case Lisp_Object_Type::Keyword: {
             Drawn_Area colon =  draw_text(":", "#c61b6e");
             write_x += colon.width;
-            Drawn_Area text = draw_text(&obj->value.identifier->data, "#c61b6e");
+            Drawn_Area text = draw_text(&obj->value.symbol.identifier->data, "#c61b6e");
             write_x -= colon.width;
             return {
                 colon.x,
@@ -179,8 +179,12 @@ proc visualize_lisp_machine() -> void {
                 colon.height
             };
         }
-        case Lisp_Object_Type::String:  return draw_text(&obj->value.string->data, "#2aa198", true, 20);
-        default: return {0};
+        case Lisp_Object_Type::String:    return draw_text(&obj->value.string->data, "#2aa198", true, 20);
+        case Lisp_Object_Type::Function:  return draw_text("Function", "#aa1100");
+        case Lisp_Object_Type::CFunction: return draw_text("CFunction", "#11aa00");
+        default:
+            fprintf(stderr, "Do not know hot to visualize type %d\n", Memory::get_type(obj));
+            return {0};
         }
     };
     draw_pair = [&](Lisp_Object* pair) -> Drawn_Area {
@@ -439,7 +443,7 @@ proc visualize_lisp_machine() -> void {
             draw_new_line();
             write_x = start_x;
 
-            draw_text(&symbols->data[i]->value.identifier->data);
+            draw_text(&symbols->data[i]->value.symbol.identifier->data);
         }