macros

bin/pre.slime

@@ -1,5 +1,37 @@
 (define nil ())
 
+(define pe
+  (macro (expr)
+    (print expr)
+    (print " evaluates to -> ")
+    (print (eval expr))
+    (print "
+")
+    nil))
+
+
+(define apply
+  (lambda (fun seq)
+    (eval (pair fun seq))))
+
+(define defun
+  (macro (name params :rest body)
+         (printf "name" params "params" params "body" body)
+    (define name
+      (lambda (params) body))))
+
+(define when
+  (macro (test :rest body)
+    (if (eval test)
+        (apply prog body)
+      nil)))
+
+(define unless
+  (macro (test :rest body)
+    (if (eval test)
+        nil
+      (apply prog body))))
+
 (define nil?
   (lambda (x)
     "Checks if the argument is nil."
@@ -41,14 +73,14 @@ defined by the key 'from' and ends with the number defined in
       nil)))
 
 (define map
-  (lambda (function sequence)
+  (lambda (fun seq)
     "Takes a sequence and a function as arguments and returns a
 new sequence which contains the results of using the first
 sequences elemens as argument to that function."
-    (if (nil? sequence)
-        sequence
-      (pair (function (first sequence))
-            (map (rest sequence) function)))))
+    (if (nil? seq)
+        seq
+      (pair (fun (first seq))
+            (map fun (rest seq))))))
 
 (define reduce
   (lambda (function sequence)
@@ -56,7 +88,7 @@ sequences elemens as argument to that function."
 function to the argument sequence. This only works correctly if the
 given function accepts a variable amount of parameters. If your
 funciton is limited to two arguments, use `reduce-binary' instead."
-    (eval (pair function sequence))))
+    (apply function sequence)))
 
 (define reduce-binary
   (lambda (function sequence)
@@ -78,15 +110,19 @@ as compared to `reduce'."
                 (filter (rest sequence) function))
         (filter (rest sequence) function)))))
 
-(define printf
-  (lambda (:keys sep :defaults-to " " end :defaults-to "\n" :rest args)
-    (if (and (nil? (first args)) (nil? (rest args)))
-        (print end)
+(define printf-quoted
+  (macro (:keys sep :defaults-to " " end :defaults-to "\n" :rest args)
+    (if (nil? args)
+        (prog (print (eval end)) nil)
       (prog
        (print (first args))
-       (if (not (nil? (rest args)))
-           (print sep))
-       ;; TODO(Felix): later we should use `extend' here:
-       ;; (eval (extend (quote (printf :sep sep :end end)) (rest args)))
-       (eval (extend '(printf :sep sep :end end) (rest args)))
-       nil))))
+       (when (not (nil? (rest args))) (print (eval sep)))
+       (define command-args (list :sep (eval sep) :end (eval end)))
+       (append command-args (rest args))
+       (apply printf-quoted command-args)))))
+
+(define printf
+  (lambda (:keys sep :defaults-to " " end :defaults-to "\n" :rest args)
+    (define command-args (list :sep (eval sep) :end (eval end)))
+    (append command-args args)
+    (apply printf-quoted command-args)))

src/ast.c

@@ -97,6 +97,7 @@ void append_to_keyword_argument_list(Keyword_Arguments* args,
 
 
 typedef struct {
+    bool is_macro;
     char*  docstring;
     Positional_Arguments* positional_arguments;
     Keyword_Arguments*    keyword_arguments;
@@ -126,6 +127,7 @@ typedef enum {
     Built_In_Define,
     Built_In_Mutate,
     Built_In_Lambda,
+    Built_In_Macro,
     Built_In_Eval,
     Built_In_Quote,
     Built_In_Prog,
@@ -159,6 +161,7 @@ char* Built_In_Name_to_string(Built_In_Name name) {
     case Built_In_Less_Equal:     return "<=";
     case Built_In_List:           return "list";
     case Built_In_Load:           return "load";
+    case Built_In_Macro:          return "macro";
     case Built_In_Multiplication: return "*";
     case Built_In_Mutate:         return "mutate";
     case Built_In_Not:            return "not";
@@ -265,6 +268,7 @@ Ast_Node* create_ast_node_built_in_function(char* name) {
     else if (string_equal(name, "define")) type = Built_In_Define;
     else if (string_equal(name, "mutate")) type = Built_In_Mutate;
     else if (string_equal(name, "lambda")) type = Built_In_Lambda;
+    else if (string_equal(name, "macro"))  type = Built_In_Macro;
     else if (string_equal(name, "eval"))   type = Built_In_Eval;
     else if (string_equal(name, "quote"))  type = Built_In_Quote;
     else if (string_equal(name, "prog"))   type = Built_In_Prog;

src/eval.c

@@ -308,37 +308,6 @@ int list_length(Ast_Node* node) {
     return 0;
 }
 
-/**
-   Copies a list, in that it creates a new list, however the items are
-   the same as in the original (same pointers). This is needed to copy
-   a list when evaluating a parameters list, but not wanting to change
-   the parameters list. This happens if you have someting like:
-
-   (define a 10)
-   (define condition (quote (= a 10)))
-   (eval condition)
-   > 1.00000
-
-   If we wouldn't copy the parameters list, after calling eval would
-   be baked into the quoted list. So even after changing a, the result
-   of (eval condition) would be 1.00000.
-**/
-/* Ast_Node* copy_list(Ast_Node* node) { */
-/*     // we don't copy immutables in here */
-/*     if (node->type != Ast_Node_Type_Pair) { */
-/*         return node; */
-/*     } */
-
-/*     Ast_Node* result = new(Ast_Node); */
-/*     result->type = Ast_Node_Type_Pair; */
-/*     result->value.pair = new(Pair); */
-
-/*     result->value.pair->first = copy_list(node->value.pair->first); */
-/*     result->value.pair->rest  = copy_list(node->value.pair->rest); */
-
-/*     return result; */
-/* } */
-
 bool is_truthy (Ast_Node* expression, Environment* env);
 
 Ast_Node* extract_keyword_value(char* keyword, Parsed_Arguments* args) {
@@ -385,6 +354,7 @@ Ast_Node* eval_expr(Ast_Node* node, Environment* env) {
         create_error(_type, node);              \
         return nullptr;                         \
     }
+    
     if (error)
         return nullptr;
 
@@ -422,6 +392,7 @@ Ast_Node* eval_expr(Ast_Node* node, Environment* env) {
         // check for special form
         if (operator->type == Ast_Node_Type_Built_In_Function) {
             switch (operator->value.built_in_function->type) {
+            case Built_In_Macro:
             case Built_In_Lambda: {
                 /*
                  *  (lambda ())
@@ -435,6 +406,12 @@ Ast_Node* eval_expr(Ast_Node* node, Environment* env) {
 
 
                 Function* function = new(Function);
+                if (operator->value.built_in_function->type == Built_In_Macro) {
+                    function->is_macro = true;
+                } else {
+                    function->is_macro = false;
+                }
+
                 // if parameters were specified
                 if (arguments->value.pair->first->type != Ast_Node_Type_Nil) {
                     try {
@@ -739,10 +716,14 @@ Ast_Node* eval_expr(Ast_Node* node, Environment* env) {
         }
 
         // assume it's lambda function and evaluate the arguments
-        try {
-            arguments = eval_arguments(arguments, env, &arguments_length);
-        }
+
         if (operator->type == Ast_Node_Type_Function) {
+            if (!operator->value.function->is_macro) {
+                try {
+                    arguments = eval_arguments(arguments, env, &arguments_length);
+                }
+            }
+
             Ast_Node* result;
             try {
                 result = apply_arguments_to_function(arguments, operator->value.function, env);
@@ -750,9 +731,7 @@ Ast_Node* eval_expr(Ast_Node* node, Environment* env) {
             return result;
         }
     }
-
     default: {
-        printf("wtf???????????");
         report_error(Error_Type_Not_A_Function);
     }
     }