.gitignore

@@ -1 +1,3 @@
-*.o
+*.o
+sexc
+sex-tests

semen.scm

@@ -79,8 +79,35 @@
                                 (cons (car module-public-forms)
                                       acc))))))
 
+(define (semen-macro-expand form)
+  "Walk the form recursively and expand all macros, until none is left."
+  (semen-walk-form
+   form
+   (lambda (subform)
+     (if (sex-macro? subform)
+         (apply-macro subform)
+         subform))))
+
+;;; TODO: for greater inspiration, see SBCL's walk.lisp
+(define (semen-walk-form form walk-fn)
+  (if (atom? form) form
+      (let ((new-form (walk-fn form)))
+        (cond ((not (eq? form new-form))
+               (semen-walk-form new-form walk-fn))
+              (else (recons
+                     new-form
+                     (semen-walk-form (car new-form) walk-fn)
+                     (semen-walk-form (cdr new-form) walk-fn)))))))
+
+(define (recons old-cons new-car new-cdr)
+  (if (and (eq? new-car (car old-cons))
+           (eq? new-cdr (cdr old-cons)))
+      old-cons
+      (cons new-car new-cdr)))
+
 (define (process-fn sex-fn acc)
-  (cons sex-fn acc))
+  (let ((expanded (semen-macro-expand sex-fn)))
+    (cons expanded acc)))
 
 (define (process-struct sex-struct acc)
   (cons sex-struct acc))

tests/semen.scm

@@ -23,12 +23,31 @@
 (test '(pub fn float sum ((int a) (int b))) (sex-fn-prototype sum-fn))
 (test '((return (cast float (+ a b)))) (sex-fn-body sum-fn))
 
-(define sex-code
-  '((defmacro (sum-var name a b c)
-      `(var ,name ,(+ a b c)))
+(let ((sex-code
+       '((defmacro (sum-var name a b c)
+           `(var ,name ,(+ a b c)))
 
-    (sum-var v 1 2 3)))
+         (sum-var v 1 2 3))))
 
-(test '((var v 6)) (semen-process sex-code))
+  (test '((var v 6)) (semen-process sex-code)))
+
+;;; Macro expansion
+
+(test 'a (semen-walk-form 'a identity))
+(test '(a b c) (semen-walk-form '(a b c) identity))
+
+(test 'a (semen-macro-expand 'a))
+(test '(a b c) (semen-macro-expand '(a b c)))
+
+(let ((sex-code-macro
+       '((defmacro (x10 a)
+           `(* 10 ,a))
+
+         (fn void foo ((int a) (int b))
+             (return (+ a (x10 b)))))))
+
+  (test '((fn void foo ((int a) (int b))
+              (return (+ a (* 10 b)))))
+        (semen-process sex-code-macro)))
 
 (test-end)