diff --git a/build.bat b/build.bat
index 09e3643..3b8fbf4 100644
--- a/build.bat
+++ b/build.bat
@@ -1,26 +1,25 @@
 @echo off
+@setlocal
 pushd %~dp0
 
+set start=%time%
+
 set exeName=lisp.exe
 set binDir=bin
 
-mkdir quickbuild
+mkdir quickbuild 2>nul
 pushd quickbuild
 
-cl^
-   ../src/main.c^
-   /Fe%exeName% /W3 /TC^
-   /nologo /EHsc /Z7^
-   /link /incremental /debug:fastlink
+echo ---------- Compiling ----------
+call timecmd cl ../src/main.c /Fe%exeName% /W3 /TC /nologo /EHsc /Z7 /link /incremental /debug:fastlink
 
 if %errorlevel% == 0 (
    echo.
    if not exist ..\%binDir% mkdir ..\%binDir%
    move %exeName% ..\%binDir%\ > NUL
    pushd ..\%binDir%
-   echo ---------- Output start ----------
-   %exeName%
-   echo ---------- Output   end ----------
+   echo ---------- Running ----------
+   call timecmd %exeName%
    del %exeName% /S /Q > NUL
    popd
 ) else (
diff --git a/src/ast.c b/src/ast.c
index e344857..5eb5349 100644
--- a/src/ast.c
+++ b/src/ast.c
@@ -27,6 +27,7 @@ typedef struct {
 
 typedef struct {
     char* value;
+    int length;
 } String;
 
 typedef struct {
@@ -42,6 +43,7 @@ typedef struct {
 typedef struct {
     Lambda_List* parameters;
     Pair* form;
+    char* docstring;
 } Function;
 
 typedef struct {
@@ -79,11 +81,12 @@ Ast_Node* create_ast_node_number(double number) {
     return node;
 }
 
-Ast_Node* create_ast_node_string(char* str) {
+Ast_Node* create_ast_node_string(char* str, int length) {
     Ast_Node* node = new(Ast_Node);
     node->type = Ast_Node_Type_String;
     node->value.string = new(String);
     node->value.string->value = str;
+    node->value.string->length = length;
     return node;
 }
 
@@ -95,6 +98,13 @@ Ast_Node* create_ast_node_symbol(char* identifier) {
     return node;
 }
 
+Ast_Node* create_ast_node_keyword(char* keyword) {
+    Ast_Node* node = new(Ast_Node);
+    node->type = Ast_Node_Type_Keyword;
+    node->value.keyword = new(Keyword);
+    node->value.keyword->identifier = keyword;
+    return node;
+}
 
 Ast_Node* create_ast_node_built_in_function(char* identifier) {
     Ast_Node* node = new(Ast_Node);
diff --git a/src/error.c b/src/error.c
index 207c20e..1e44324 100644
--- a/src/error.c
+++ b/src/error.c
@@ -5,6 +5,7 @@ typedef enum {
     Error_Type_Symbol_Not_Defined,
     Error_Type_Not_A_Function,
     Error_Type_Not_Yet_Implemented,
+    Error_Type_Syntax_Error,
     Error_Type_Unknown_Error,
 } Error_Type;
 
@@ -38,6 +39,7 @@ char* Error_Type_to_string(Error_Type type) {
     case Error_Type_Wrong_Number_Of_Arguments: return "Wrong number of arguments";
     case Error_Type_Type_Missmatch:            return "Type Missmatch";
     case Error_Type_Not_Yet_Implemented:       return "Not yet implemented";
+    case Error_Type_Syntax_Error:              return "Syntax Error";
     default:                                   return "Unknown Error";
     }
 }
diff --git a/src/eval.c b/src/eval.c
index 008516e..f7a8224 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -81,7 +81,8 @@ Ast_Node* eval_expr(Ast_Node* node, Environment* env) {
             } else if (string_equal("if", operator_name)) {
                 int operands_length = list_length(operands);
                 if (operands_length != 2 && operands_length != 3) {
-                    create_error(Error_Type_Wrong_Number_Of_Arguments, operands);
+                    if (!error)
+                        create_error(Error_Type_Wrong_Number_Of_Arguments, operands);
                     return nullptr;
                 }
 
@@ -124,10 +125,14 @@ Ast_Node* eval_expr(Ast_Node* node, Environment* env) {
                 return create_ast_node_nil();
             } else if (string_equal("not", operator_name)) {
                 if (list_length(operands) != 1) {
-                    create_error(Error_Type_Wrong_Number_Of_Arguments, operands);
+                    if (!error)
+                        create_error(Error_Type_Wrong_Number_Of_Arguments, operands);
                     return nullptr;
                 }
-
+                bool truthy = is_truthy(operands->value.pair->first, env);
+                if (truthy)
+                    return create_ast_node_nil();
+                return create_ast_node_number(1);
             } else {
                 report_error(Error_Type_Not_Yet_Implemented);
             }
@@ -148,7 +153,7 @@ bool is_truthy (Ast_Node* expression, Environment* env) {
     Ast_Node* result = eval_expr(expression, env);
     switch (result->type) {
     case Ast_Node_Type_Nil:    return false;
-    case Ast_Node_Type_Number: return result->value.number->value != 0;
+    /* case Ast_Node_Type_Number: return result->value.number->value != 0; */
     default:                   return true;
     }
 }
diff --git a/src/parse.c b/src/parse.c
index 7ce6d2a..420b555 100644
--- a/src/parse.c
+++ b/src/parse.c
@@ -1,12 +1,257 @@
-Ast_Node* parse_expression(char* expr) {
-    typedef enum {
-        Parser_State_Code,
-        Parser_State_String,
-        Parser_State_Comment,
-    } Parser_State;
+typedef struct {
+    Ast_Node** data;
+    int length;
+    int next_index;
+} Ast_Node_Array_List;
 
-    // initial state is code
-    Parser_State current_parser_state = Parser_State_Code;
+Ast_Node_Array_List* create_Ast_Node_Array_List() {
+    Ast_Node_Array_List* ret = new (Ast_Node_Array_List);
 
-    return nullptr;
+    // create one with 16 entries first
+    ret->length = 16;
+    ret->data = (Ast_Node**)malloc(ret->length * sizeof(Ast_Node));
+    ret->next_index = 0;
+
+    return ret;
+}
+
+void append_to_Ast_Node_Array_List(Ast_Node_Array_List* list, Ast_Node* node) {
+    if (list->next_index == list->length) {
+        list->length *= 2;
+        list->data =
+            (Ast_Node**)realloc(list->data, list->length * sizeof(Ast_Node));
+    }
+
+    list->data[list->next_index++] = node;
+}
+
+void eat_comment_line(char* text, int* index_in_text) {
+    // safety check if we are actually starting a comment here
+    if (text[*index_in_text] != ';')
+        return;
+
+    // eat the comment line
+    do {
+        ++(*index_in_text);
+    } while (text[(*index_in_text)] != '\n' &&
+             text[(*index_in_text)] != '\0');
+}
+
+void eat_whitespace(char* text, int* index_in_text) {
+    // skip whitespaces
+    while (text[(*index_in_text)] == ' '  ||
+           text[(*index_in_text)] == '\t' ||
+           text[(*index_in_text)] == '\n') {
+        ++(*index_in_text);
+    }
+}
+
+void eat_until_code(char* text, int* index_in_text) {
+    int position_before;
+    do {
+        position_before = *index_in_text;
+        eat_comment_line(text, index_in_text);
+        eat_whitespace(text, index_in_text);
+    } while (position_before != *index_in_text);
+}
+
+char* read_atom(char* text, int* index_in_text) {
+    int atom_length = 0;
+    while (text[*index_in_text+atom_length] != ' '  &&
+           text[*index_in_text+atom_length] != ')'  &&
+           text[*index_in_text+atom_length] != '('  &&
+           text[*index_in_text+atom_length] != '\0' &&
+           text[*index_in_text+atom_length] != '\n' &&
+           text[*index_in_text+atom_length] != '\t')
+    {
+        ++atom_length;
+    }
+
+    // let's mark the end of the atom there quickly, so the string can
+    // be copied from there easily and then put the char that was
+    // before there back
+    char before = text[*index_in_text+atom_length];
+    text[*index_in_text+atom_length] = '\0';
+
+    // get the atom
+    char* atom = (char*)malloc(atom_length*sizeof(char)+1); // plus null char
+    strcpy(atom, text+(*index_in_text));
+
+    // restore the original string
+    text[*index_in_text+atom_length] = before;
+
+    // update the index to point to the character after the atom
+    // ended
+    *index_in_text += atom_length;
+
+    return atom;
+}
+
+Ast_Node* parse_number(char* text, int* index_in_text) {
+    double number;
+    char* str_number = read_atom(text, index_in_text);
+    sscanf(str_number, "%lf", &number);
+    return create_ast_node_number(number);
+}
+
+
+Ast_Node* parse_keyword(char* text, int* index_in_text) {
+    // we are now on the colon
+    ++(*index_in_text);
+    char* str_keyword = read_atom(text, index_in_text);
+    return create_ast_node_keyword(str_keyword);
+}
+
+Ast_Node* parse_symbol(char* text, int* index_in_text) {
+    // we are now at the first char of the symbol
+    char* str_symbol = read_atom(text, index_in_text);
+    return create_ast_node_symbol(str_symbol);
+}
+
+Ast_Node* parse_string(char* text, int* index_in_text) {
+    // the first character is the '"'
+    ++(*index_in_text);
+
+    // now we are at the first letter, if this is the closing '"' then
+    // it's easy
+    if (text[*index_in_text] == '"') {
+        char* str = new(char);
+        *str = '\0';
+        return create_ast_node_string(str, 0);
+    }
+
+    // okay so the first letter was not actually closing the string...
+    int string_length = 0;
+    while (text[*index_in_text+string_length] != '"' ||
+           text[*index_in_text+string_length] == '\\')
+    {
+        ++string_length;
+    }
+
+    // we found the end of the string
+    text[*index_in_text+string_length] = '\0';
+
+    char* string = (char*)malloc(string_length*sizeof(char)+1); // plus null char
+    strcpy(string, text+(*index_in_text));
+
+    text[*index_in_text+string_length] = '"';
+
+    *index_in_text += string_length +1; // plus one because we want to
+                                        // go after the quotes
+
+    return create_ast_node_string(string, string_length);
+}
+
+Ast_Node* parse_atom(char* text, int* index_in_text) {
+    // numbers
+    if ((text[*index_in_text] <= 57 &&   // if number
+         text[*index_in_text] >= 48)
+        ||
+        ((text[*index_in_text] == '+' || // or if sign and then number
+          text[*index_in_text] == '-')
+            &&
+         (text[*index_in_text +1] <= 57 &&
+          text[*index_in_text +1] >= 48))
+        ||
+        ((text[*index_in_text] == '.')  // or if . and then number
+         &&
+         (text[*index_in_text +1] <= 57 &&
+          text[*index_in_text +1] >= 48)))
+        return parse_number(text, index_in_text);
+
+    // keywords
+    if (text[*index_in_text] == ':')
+        return parse_keyword(text, index_in_text);
+
+    // strings
+    if (text[*index_in_text] == '"')
+        return parse_string(text, index_in_text);
+
+    return parse_symbol(text, index_in_text);
+}
+
+Ast_Node* parse_expression(char* text, int* index_in_text) {
+    // okay we know the text under the index is '('
+    ++(*index_in_text);
+
+    eat_whitespace(text, index_in_text);
+
+    // if there was actually nothing in the list return nil
+    if (text[(*index_in_text)] == ')') {
+        ++(*index_in_text);
+        return create_ast_node_nil();
+    }
+
+    // okay there is something
+    Ast_Node* head = new(Ast_Node);
+    head->type = Ast_Node_Type_Pair;
+    head->value.pair = new(Pair);
+    Ast_Node* expression = head;
+
+    while (true) {
+        if (text[(*index_in_text)] == '(') {
+            head->value.pair->first = parse_expression(text, index_in_text);
+        } else {
+            head->value.pair->first = parse_atom(text, index_in_text);
+        }
+
+        eat_until_code(text, index_in_text);
+
+        if (text[(*index_in_text)] == ')') {
+            head->value.pair->rest = create_ast_node_nil();
+            ++(*index_in_text);
+            break;
+        } else if (text[(*index_in_text)] == '.') {
+            ++(*index_in_text);
+            eat_until_code(text, index_in_text);
+
+            if (text[(*index_in_text)] == '(')
+                head->value.pair->rest = parse_expression(text, index_in_text);
+            else
+                head->value.pair->rest = parse_atom(text, index_in_text);
+
+            eat_until_code(text, index_in_text);
+
+            if (text[(*index_in_text)] != ')')
+                create_error(Error_Type_Syntax_Error, nullptr);
+            ++(*index_in_text);
+            break;
+        } else {
+            head->value.pair->rest = create_ast_node_pair(nullptr, nullptr);
+            head = head->value.pair->rest;
+        }
+    }
+    return expression;
+}
+
+Ast_Node* parse_single_expression(char* text) {
+    int index_in_text = 0;
+    return parse_expression(text, &index_in_text);
+}
+
+Ast_Node_Array_List* parse_program(char* text) {
+    Ast_Node_Array_List* program = create_Ast_Node_Array_List();
+
+    int index_in_text = 0;
+
+    while (text[index_in_text] != '\0') {
+        switch (text[index_in_text]) {
+        case '(': {
+            append_to_Ast_Node_Array_List(
+                program, parse_expression(text, &index_in_text));
+        } break;
+        case ';': {
+            eat_comment_line(text, &index_in_text);
+        } break;
+        case ' ':
+        case '\t':
+        case '\n': {
+            ++index_in_text;
+        } break;
+        default:
+            create_error(Error_Type_Syntax_Error, nullptr);
+            /* syntax error */
+        }
+    }
+    return program;
 }
diff --git a/src/testing.c b/src/testing.c
index 0dcbbdf..8c7aa3d 100644
--- a/src/testing.c
+++ b/src/testing.c
@@ -4,16 +4,14 @@
 #define pass 1
 #define fail 0
 
-#define print_assert_equal_fail(variable, value, type, format)  \
-    printf("\nAssertion failed for '" #variable "'"             \
-           "\n\t  in %s:%d"                                     \
-           "\n\texpected: " format                              \
-           "\n\tgot:      " format "\n",                        \
-           __FILE__, __LINE__, (type)value, (type)variable)
+#define print_assert_equal_fail(variable, value, type, format)          \
+    printf("\n%s:%d: Assertion failed\n\tfor '" #variable "'"           \
+        "\n\texpected: " format                                         \
+        "\n\tgot:      " format "\n",                                   \
+        __FILE__, __LINE__, (type)value, (type)variable)
 
 #define print_assert_not_equal_fail(variable, value, type, format)      \
-    printf("\nAssertion failed for '" #variable "'"                     \
-           "\n\t  in %s:%d"                                             \
+    printf("\n%s:%d: Assertion failed\n\tfor '" #variable "'"           \
            "\n\texpected not: " format                                  \
            "\n\tgot anyways:  " format "\n",                            \
            __FILE__, __LINE__, (type)value, (type)variable)
@@ -50,6 +48,13 @@
         return fail;                                                    \
     }
 
+#define assert_equal_string(variable, value)                            \
+    if (!string_equal(variable, value)) {                               \
+        print_assert_equal_fail(variable, value, char*, "%s");          \
+        return fail;                                                    \
+    }
+
+
 #define assert_null(variable)                   \
     assert_equal_int(variable, nullptr)
 
@@ -74,21 +79,121 @@
         }                                                       \
     }                                                           \
 
+testresult test_parse_atom() {
+    int index_in_text = 0;
+    char string[] =
+        "123 -1.23e-2 " // numbers
+        "\"asd\" "      // strings
+        ":key1 :key:2 " // keywords
+        "sym +";        // symbols
+
+    // test numbers
+    Ast_Node* result = parse_atom(string, &index_in_text);
+    assert_equal_int(result->type, Ast_Node_Type_Number);
+    assert_equal_double(result->value.number->value, 123);
+
+    ++index_in_text;
+
+    result = parse_atom(string, &index_in_text);
+    assert_equal_int(result->type, Ast_Node_Type_Number);
+    assert_equal_double(result->value.number->value, -1.23e-2);
+
+    // test strings
+    ++index_in_text;
+
+    result = parse_atom(string, &index_in_text);
+    assert_equal_int(result->type, Ast_Node_Type_String);
+    assert_equal_string(result->value.string->value, "asd");
+
+    // test keywords
+    ++index_in_text;
+
+    result = parse_atom(string, &index_in_text);
+    assert_equal_int(result->type, Ast_Node_Type_Keyword);
+    assert_equal_string(result->value.keyword->identifier, "key1");
+
+    ++index_in_text;
+
+    result = parse_atom(string, &index_in_text);
+    assert_equal_int(result->type, Ast_Node_Type_Keyword);
+    assert_equal_string(result->value.keyword->identifier, "key:2");
+
+    // test symbols
+    ++index_in_text;
+
+    result = parse_atom(string, &index_in_text);
+    assert_equal_int(result->type, Ast_Node_Type_Symbol);
+    assert_equal_string(result->value.symbol->identifier, "sym");
+
+    ++index_in_text;
+
+    result = parse_atom(string, &index_in_text);
+    assert_equal_int(result->type, Ast_Node_Type_Symbol);
+    assert_equal_string(result->value.symbol->identifier, "+");
+
+    return pass;
+}
+
+testresult test_parse_expression() {
+    int index_in_text = 0;
+    char string[] = "(fun + 12)";
+
+    Ast_Node* result = parse_expression(string, &index_in_text);
+    assert_no_error(error);
+
+    assert_equal_int(result->type, Ast_Node_Type_Pair);
+    assert_equal_int(result->value.pair->first->type, Ast_Node_Type_Symbol);
+    assert_equal_string(result->value.pair->first->value.symbol->identifier, "fun");
+
+    result = result->value.pair->rest;
+
+    assert_equal_int(result->type, Ast_Node_Type_Pair);
+    assert_equal_int(result->value.pair->first->type, Ast_Node_Type_Symbol);
+    assert_equal_string(result->value.pair->first->value.symbol->identifier, "+");
+
+    result = result->value.pair->rest;
+
+    assert_equal_int(result->type, Ast_Node_Type_Pair);
+    assert_equal_int(result->value.pair->first->type, Ast_Node_Type_Number);
+    assert_equal_double(result->value.pair->first->value.number->value, 12);
+
+    result = result->value.pair->rest;
+
+    assert_equal_int(result->type, Ast_Node_Type_Nil);
+
+    char string2[] = "(define fun (lambda (x) (+ 5 (* x x ))))";
+    index_in_text = 0;
+
+    result = parse_expression(string2, &index_in_text);
+    assert_no_error(error);
+
+    assert_equal_int(result->type, Ast_Node_Type_Pair);
+    assert_equal_int(result->value.pair->first->type, Ast_Node_Type_Symbol);
+    assert_equal_string(result->value.pair->first->value.symbol->identifier, "define");
+
+    result = result->value.pair->rest;
+
+    assert_equal_int(result->type, Ast_Node_Type_Pair);
+    assert_equal_int(result->value.pair->first->type, Ast_Node_Type_Symbol);
+    assert_equal_string(result->value.pair->first->value.symbol->identifier, "fun");
+
+    result = result->value.pair->rest;
+
+    assert_equal_int(result->type, Ast_Node_Type_Pair);
+    assert_equal_int(result->value.pair->first->type, Ast_Node_Type_Pair);
+    assert_equal_int(result->value.pair->first->value.pair->first->type, Ast_Node_Type_Symbol);
+    assert_equal_string(result->value.pair->first->value.pair->first->value.symbol->identifier, "lambda");
+
+    result = result->value.pair->rest;
+
+
+    return pass;
+}
 
 testresult test_built_in_add() {
-    Ast_Node* plus = create_ast_node_symbol("+");
-    Ast_Node* ten  = create_ast_node_number(10);
-    Ast_Node* four = create_ast_node_number(4);
-    Ast_Node* nil  = create_ast_node_nil();
-    Ast_Node* form = create_ast_node_pair(
-        plus,
-        create_ast_node_pair(
-            ten,
-            create_ast_node_pair(
-                four,
-                nil)));
-
-    Ast_Node* result = eval_expr(form, create_empty_environment());
+    char exp_string[] = "(+ 10 4)";
+    Ast_Node* expression = parse_single_expression(exp_string);
+    Ast_Node* result = eval_expr(expression, create_empty_environment());
 
     assert_no_error(error);
     assert_not_null(result);
@@ -99,19 +204,9 @@ testresult test_built_in_add() {
 }
 
 testresult test_built_in_substract() {
-    Ast_Node* minus = create_ast_node_symbol("-");
-    Ast_Node* ten   = create_ast_node_number(10);
-    Ast_Node* four  = create_ast_node_number(4);
-    Ast_Node* nil   = create_ast_node_nil();
-    Ast_Node* form  = create_ast_node_pair(
-        minus,
-        create_ast_node_pair(
-            ten,
-            create_ast_node_pair(
-                four,
-                nil)));
-
-    Ast_Node* result = eval_expr(form, create_empty_environment());
+    char exp_string[] = "(- 10 4)";
+    Ast_Node* expression = parse_single_expression(exp_string);
+    Ast_Node* result = eval_expr(expression, create_empty_environment());
 
     assert_no_error(error);
     assert_not_null(result);
@@ -123,19 +218,9 @@ testresult test_built_in_substract() {
 
 
 testresult test_built_in_multiply() {
-    Ast_Node* times = create_ast_node_symbol("*");
-    Ast_Node* ten  = create_ast_node_number(10);
-    Ast_Node* four = create_ast_node_number(4);
-    Ast_Node* nil  = create_ast_node_nil();
-    Ast_Node* form = create_ast_node_pair(
-        times,
-        create_ast_node_pair(
-            ten,
-            create_ast_node_pair(
-                four,
-                nil)));
-
-    Ast_Node* result = eval_expr(form, create_empty_environment());
+    char exp_string[] = "(* 10 4)";
+    Ast_Node* expression = parse_single_expression(exp_string);
+    Ast_Node* result = eval_expr(expression, create_empty_environment());
 
     assert_no_error(error);
     assert_not_null(result);
@@ -147,19 +232,9 @@ testresult test_built_in_multiply() {
 
 
 testresult test_built_in_divide() {
-    Ast_Node* over = create_ast_node_symbol("/");
-    Ast_Node* ten  = create_ast_node_number(20);
-    Ast_Node* four = create_ast_node_number(4);
-    Ast_Node* nil  = create_ast_node_nil();
-    Ast_Node* form = create_ast_node_pair(
-        over,
-        create_ast_node_pair(
-            ten,
-            create_ast_node_pair(
-                four,
-                nil)));
-
-    Ast_Node* result = eval_expr(form, create_empty_environment());
+    char exp_string[] = "(/ 20 4)";
+    Ast_Node* expression = parse_single_expression(exp_string);
+    Ast_Node* result = eval_expr(expression, create_empty_environment());
 
     assert_null(error);
     assert_not_null(result);
@@ -171,35 +246,20 @@ testresult test_built_in_divide() {
 
 
 testresult test_built_in_if() {
-    Ast_Node* _if    = create_ast_node_symbol("if");
-    Ast_Node* cond   = create_ast_node_number(1);
-    Ast_Node* four   = create_ast_node_number(4);
-    Ast_Node* five   = create_ast_node_number(5);
-    Ast_Node* nil    = create_ast_node_nil();
-    Ast_Node* form   = create_ast_node_pair(
-        _if,
-        create_ast_node_pair(
-            cond,
-            create_ast_node_pair(
-                four,
-                create_ast_node_pair(
-                    five,
-                    nil))));
-    Ast_Node* result;
-
-    // test *then* case
-    result = eval_expr(form, create_empty_environment());
+    char exp_string1[] = "(if 1 4 5)";
+    Ast_Node* expression = parse_single_expression(exp_string1);
+    Ast_Node* result = eval_expr(expression, create_empty_environment());
 
     assert_no_error(error);
     assert_not_null(result);
     assert_equal_int(result->type, Ast_Node_Type_Number);
     assert_equal_double(result->value.number->value, 4);
 
-    // test *else* case
-    cond->value.number->value = 0;
-                       result = eval_expr(form, create_empty_environment());
+    char exp_string2[] = "(if () 4 5)";
+    expression = parse_single_expression(exp_string2);
+    result = eval_expr(expression, create_empty_environment());
 
-    assert_null(error);
+    assert_no_error(error);
     assert_not_null(result);
     assert_equal_int(result->type, Ast_Node_Type_Number);
     assert_equal_double(result->value.number->value, 5);
@@ -208,24 +268,9 @@ testresult test_built_in_if() {
 }
 
 testresult test_built_in_and() {
-    Ast_Node* _and  = create_ast_node_symbol("and");
-    Ast_Node* cond1 = create_ast_node_number(1);
-    Ast_Node* cond2 = create_ast_node_string("asd");
-    Ast_Node* cond3 = create_ast_node_number(4);
-    Ast_Node* nil   = create_ast_node_nil();
-    Ast_Node* form  = create_ast_node_pair(
-        _and,
-        create_ast_node_pair(
-            cond1,
-            create_ast_node_pair(
-                cond2,
-                create_ast_node_pair(
-                    cond3,
-                    nil))));
-    Ast_Node* result;
-
-    // a true case
-    result = eval_expr(form, create_empty_environment());
+    char exp_string1[] = "(and 1 \"asd\" 4)";
+    Ast_Node* expression = parse_single_expression(exp_string1);
+    Ast_Node* result = eval_expr(expression, create_empty_environment());
 
     assert_no_error(error);
     assert_not_null(result);
@@ -233,8 +278,9 @@ testresult test_built_in_and() {
     assert_equal_double(result->value.number->value, 1);
 
     // a false case
-    cond1->value.number->value = 0;
-                       result = eval_expr(form, create_empty_environment());
+    char exp_string2[] = "(and () \"asd\" 4)";
+    expression = parse_single_expression(exp_string2);
+    result = eval_expr(expression, create_empty_environment());
 
     assert_no_error(error);
     assert_not_null(result);
@@ -244,20 +290,9 @@ testresult test_built_in_and() {
 }
 
 testresult test_built_in_or() {
-    Ast_Node* _or   = create_ast_node_symbol("or");
-    Ast_Node* cond1 = create_ast_node_nil();
-    Ast_Node* cond2 = create_ast_node_string("asd");
-    Ast_Node* nil   = create_ast_node_nil();
-    Ast_Node* form  = create_ast_node_pair(
-        _or,
-        create_ast_node_pair(
-            cond1,
-            create_ast_node_pair(
-                cond2, nil)));
-    Ast_Node* result;
-
-    // a true case
-    result = eval_expr(form, create_empty_environment());
+    char exp_string1[] = "(or \"asd\" nil)";
+    Ast_Node* expression = parse_single_expression(exp_string1);
+    Ast_Node* result = eval_expr(expression, create_empty_environment());
 
     assert_no_error(error);
     assert_not_null(result);
@@ -265,14 +300,9 @@ testresult test_built_in_or() {
     assert_equal_double(result->value.number->value, 1);
 
     // a false case
-    cond2 = create_ast_node_nil();
-    form  = create_ast_node_pair(
-        _or,
-        create_ast_node_pair(
-            cond1,
-            create_ast_node_pair(
-                cond2, nil)));
-    result = eval_expr(form, create_empty_environment());
+    char exp_string2[] = "(or () ())";
+    expression = parse_single_expression(exp_string2);
+    result = eval_expr(expression, create_empty_environment());
 
     assert_no_error(error);
     assert_not_null(result);
@@ -282,9 +312,37 @@ testresult test_built_in_or() {
 }
 
 
+testresult test_built_in_not() {
+    char exp_string1[] = "(not ())";
+    Ast_Node* expression = parse_single_expression(exp_string1);
+    Ast_Node* result = eval_expr(expression, create_empty_environment());
+
+    // a true case
+    assert_no_error(error);
+    assert_not_null(result);
+    assert_equal_int(result->type, Ast_Node_Type_Number);
+    assert_equal_double(result->value.number->value, 1);
+
+    // a false case
+    char exp_string2[] = "(not \"asd xD\")";
+    expression = parse_single_expression(exp_string2);
+    result = eval_expr(expression, create_empty_environment());
+
+    assert_no_error(error);
+    assert_not_null(result);
+    assert_equal_int(result->type, Ast_Node_Type_Nil);
+
+    return pass;
+}
+
 void run_all_tests() {
     log_level = Log_Level_None;
 
+    printf("-- Parsing --\n");
+    invoke_test(test_parse_atom);
+    invoke_test(test_parse_expression);
+
+    printf("\n-- Built ins --\n");
     invoke_test(test_built_in_add);
     invoke_test(test_built_in_substract);
     invoke_test(test_built_in_multiply);
@@ -292,5 +350,7 @@ void run_all_tests() {
     invoke_test(test_built_in_if);
     invoke_test(test_built_in_and);
     invoke_test(test_built_in_or);
+    invoke_test(test_built_in_not);
+
 
 }
diff --git a/todo.org b/todo.org
index f23a0fc..82915cf 100644
--- a/todo.org
+++ b/todo.org
@@ -1,3 +1,4 @@
+* TODO =assert_equal_type= macro in testing
 * Build-in forms
 
 ** DONE +