implemented error

src/ast.c

@@ -130,6 +130,7 @@ typedef enum {
     Built_In_Division,
     Built_In_Equal,
     Built_In_Eval,
+    Built_In_Error,
     Built_In_Exit,
     Built_In_First,
     Built_In_Greater,
@@ -170,6 +171,7 @@ char* Built_In_Name_to_string(Built_In_Name name) {
     case Built_In_Define:         return "define";
     case Built_In_Division:       return "/";
     case Built_In_Equal:          return "=";
+    case Built_In_Error:          return "error";
     case Built_In_Eval:           return "eval";
     case Built_In_Exit:           return "exit";
     case Built_In_First:          return "first";
@@ -291,6 +293,7 @@ Ast_Node* create_ast_node_built_in_function(char* name) {
     else if (string_equal(name, "and"))          type = Built_In_And;
     else if (string_equal(name, "breakpoint"))   type = Built_In_Breakpoint;
     else if (string_equal(name, "define"))       type = Built_In_Define;
+    else if (string_equal(name, "error"))        type = Built_In_Error;
     else if (string_equal(name, "eval"))         type = Built_In_Eval;
     else if (string_equal(name, "exit"))         type = Built_In_Exit;
     else if (string_equal(name, "first"))        type = Built_In_First;

src/eval.c

@@ -846,6 +846,12 @@ Ast_Node* eval_expr(Ast_Node* node, Environment* env) {
             case Built_In_List: {
                 return evaluated_arguments;
             }
+            case Built_In_Error: {
+                if (arguments_length != 0) {
+                    report_error(Error_Type_Wrong_Number_Of_Arguments);
+                }
+                report_error(Error_Type_Unknown_Error);
+            }
             case Built_In_Print: {
                 if (arguments_length != 1) {
                     report_error(Error_Type_Wrong_Number_Of_Arguments);