Data commit

Task/Metaprogramming/TXR/metaprogramming.txr

@@ -0,0 +1,26 @@
+(defmacro whil ((condition : result) . body)
+  (let ((cblk (gensym "cnt-blk-"))
+        (bblk (gensym "brk-blk-")))
+    ^(macrolet ((break (value) ^(return-from ,',bblk ,value)))
+       (symacrolet ((break (return-from ,bblk))
+                    (continue (return-from ,cblk)))
+         (block ,bblk
+           (for () (,condition ,result) ()
+             (block ,cblk ,*body)))))))
+
+(let ((i 0))
+  (whil ((< i 100))
+    (if (< (inc i) 20)
+      continue)
+    (if (> i 30)
+      break)
+    (prinl i)))
+
+(prinl
+  (sys:expand
+    '(whil ((< i 100))
+       (if (< (inc i) 20)
+         continue)
+       (if (> i 30)
+         break)
+       (prinl i))))