Hello Justin, If you grep Hoopl's source code for wrapFR and wrapBR, you can find uses of the methods. For example: thenFwdRw :: forall m n f. Monad m => FwdRewrite m n f -> FwdRewrite m n f -> FwdRewrite m n f -- @ end comb1.tex thenFwdRw rw3 rw3' = wrapFR2 thenrw rw3 rw3' where thenrw :: forall m1 e x t t1. Monad m1 => (t -> t1 -> m1 (Maybe (Graph n e x, FwdRewrite m n f))) -> (t -> t1 -> m1 (Maybe (Graph n e x, FwdRewrite m n f))) -> (t -> t1 -> m1 (Maybe (Graph n e x, FwdRewrite m n f))) thenrw rw rw' n f = rw n f >>= fwdRes where fwdRes Nothing = rw' n f fwdRes (Just gr) = return $ Just $ fadd_rw rw3' gr This usage of wrapFR2 doesn't take advantage of the extra polymorphism of wrapFR2, but it takes two forward rewrites and composes them into a single rewrite. Edward