Use while to define forLoop.

src/Control/Abstract/Value.hs

@@ -86,12 +86,7 @@ forLoop :: MonadValue term value m
 forLoop initial cond step body = do
   void initial
   env <- getGlobalEnv
-  localEnv (mappend env) (fix $ \ loop -> do
-      cond' <- cond
-      ifthenelse cond' (do
-        void body
-        void step
-        loop) unit)
+  localEnv (mappend env) (while cond (body *> step))
 
 -- | The fundamental looping primitive, built on top of ifthenelse.
 while :: MonadValue term value m => m value -> m value -> m value