Merge branch '4-t-as-a-source-of-universal-truth' into 'master'

Resolve ""t" as a source of universal truth"

Closes #4

See merge request FelixBrendel/slime!2

bin/pre.slime

@@ -1,5 +1,3 @@
-(define nil ())
-
 (define defmacro
   (macro (@name @params :rest @body)
      "Macro for creating macros with a more concise syntax."

src/ast.c

@@ -3,6 +3,7 @@ define_array_list(struct Ast_Node*, Ast_Node);
 
 typedef enum {
     Ast_Node_Type_Nil,
+    Ast_Node_Type_T,
 
     Ast_Node_Type_Symbol,
     Ast_Node_Type_Keyword,
@@ -17,6 +18,7 @@ typedef enum {
 char* Ast_Node_Type_to_string(Ast_Node_Type type) {
     switch (type) {
     case(Ast_Node_Type_Nil):               return "nil";
+    case(Ast_Node_Type_T):                 return "t";
     case(Ast_Node_Type_Number):            return "number";
     case(Ast_Node_Type_String):            return "string";
     case(Ast_Node_Type_Symbol):            return "symbol";
@@ -233,6 +235,13 @@ Ast_Node* create_ast_node_nil() {
     return node;
 }
 
+Ast_Node* create_ast_node_t() {
+    Ast_Node* node = new(Ast_Node);
+    node->type = Ast_Node_Type_T;
+    node->value.pair = nullptr;
+    return node;
+}
+
 Ast_Node* create_ast_node_number(double number) {
     Ast_Node* node = new(Ast_Node);
     node->type = Ast_Node_Type_Number;

src/built_ins.c

@@ -43,7 +43,7 @@ bool ast_node_equal(Ast_Node* n1, Ast_Node* n2) {
 
 Ast_Node* built_in_equals(Ast_Node* operands) {
     if (operands->type == Ast_Node_Type_Nil)
-        return create_ast_node_number(1);
+        return create_ast_node_t();
 
     Ast_Node* first = operands->value.pair->first;
 
@@ -53,7 +53,7 @@ Ast_Node* built_in_equals(Ast_Node* operands) {
         operands = operands->value.pair->rest;
     }
 
-    return create_ast_node_number(1);
+                                 return create_ast_node_t();
 }
 
 Ast_Node* built_in_greater(Ast_Node* operands) {
@@ -71,7 +71,7 @@ Ast_Node* built_in_greater(Ast_Node* operands) {
         operands = operands->value.pair->rest;
     }
 
-    return create_ast_node_number(1);
+    return create_ast_node_t();
 }
 
 Ast_Node* built_in_greater_equal(Ast_Node* operands) {
@@ -89,7 +89,7 @@ Ast_Node* built_in_greater_equal(Ast_Node* operands) {
         operands = operands->value.pair->rest;
     }
 
-    return create_ast_node_number(1);
+    return create_ast_node_t();
 }
 
 Ast_Node* built_in_less(Ast_Node* operands) {
@@ -107,7 +107,7 @@ Ast_Node* built_in_less(Ast_Node* operands) {
         operands = operands->value.pair->rest;
     }
 
-    return create_ast_node_number(1);
+    return create_ast_node_t();
 }
 
 Ast_Node* built_in_less_equal(Ast_Node* operands) {
@@ -125,7 +125,7 @@ Ast_Node* built_in_less_equal(Ast_Node* operands) {
         operands = operands->value.pair->rest;
     }
 
-    return create_ast_node_number(1);
+    return create_ast_node_t();
 }
 
 Ast_Node* built_in_add(Ast_Node* operands) {

src/eval.c

@@ -371,9 +371,9 @@ Ast_Node* eval_expr(Ast_Node* node, Environment* env) {
 
     Ast_Node* ret = new(Ast_Node);
     switch (node->type) {
+    case Ast_Node_Type_T:
     case Ast_Node_Type_Nil:
-        ret->type = Ast_Node_Type_Nil;
+        return node;
-        return ret;
     case Ast_Node_Type_Symbol: {
         Ast_Node* symbol;
         try {
@@ -533,7 +533,7 @@ Ast_Node* eval_expr(Ast_Node* node, Environment* env) {
                     if (!result) return create_ast_node_nil();
                 }
 
-                return create_ast_node_number(1);
+                return create_ast_node_t();
             }
             case Built_In_Or: {
                 bool result = false;
@@ -546,7 +546,7 @@ Ast_Node* eval_expr(Ast_Node* node, Environment* env) {
                     }
                     arguments = arguments->value.pair->rest;
 
-                    if (result) return create_ast_node_number(1);
+                    if (result) return create_ast_node_t();
                 }
 
                 return create_ast_node_nil();
@@ -564,7 +564,7 @@ Ast_Node* eval_expr(Ast_Node* node, Environment* env) {
                 }
                 if (truthy)
                     return create_ast_node_nil();
-                return create_ast_node_number(1);
+                return create_ast_node_t();
             }
             case Built_In_If: {
                 try {

src/io.c

@@ -29,7 +29,6 @@ void log_message(Log_Level type, char* message) {
     printf("%s: %s\n",prefix, message);
 }
 
-
 void panic(char* message) {
     log_message(Log_Level_Critical, message);
     exit(1);
@@ -40,6 +39,9 @@ void print(Ast_Node* node) {
     case (Ast_Node_Type_Nil): {
         printf("nil");
     } break;
+    case (Ast_Node_Type_T): {
+        printf("t");
+    } break;
     case (Ast_Node_Type_Number): {
         printf("%f", node->value.number->value);
     } break;

src/parse.c

@@ -101,6 +101,13 @@ Ast_Node* parse_keyword(char* text, int* index_in_text) {
 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);
+
+    if (string_equal(str_symbol, "nil")) {
+        return create_ast_node_nil();
+    }
+    if (string_equal(str_symbol, "t")) {
+        return create_ast_node_t();
+    }
     return create_ast_node_symbol(str_symbol);
 }
 

src/testing.c

@@ -314,8 +314,7 @@ testresult test_built_in_and() {
 
     assert_no_error(error);
     assert_not_null(result);
-    assert_equal_type(result, Ast_Node_Type_Number);
+    assert_equal_type(result, Ast_Node_Type_T);
-    assert_equal_double(result->value.number->value, 1);
 
     // a false case
     char exp_string2[] = "(and () \"asd\" 4)";
@@ -336,8 +335,7 @@ testresult test_built_in_or() {
 
     assert_no_error(error);
     assert_not_null(result);
-    assert_equal_type(result, Ast_Node_Type_Number);
+    assert_equal_type(result, Ast_Node_Type_T);
-    assert_equal_double(result->value.number->value, 1);
 
     // a false case
     char exp_string2[] = "(or () ())";
@@ -360,8 +358,7 @@ testresult test_built_in_not() {
     // a true case
     assert_no_error(error);
     assert_not_null(result);
-    assert_equal_type(result, Ast_Node_Type_Number);
+    assert_equal_type(result, Ast_Node_Type_T);
-    assert_equal_double(result->value.number->value, 1);
 
     // a false case
     char exp_string2[] = "(not \"asd xD\")";