Hello Creighton, Thursday, October 27, 2005, 7:54:22 PM, you wrote: CH> Haskell seems to me to be a very powerful language, and it CH> looks like it should be possible to define control CH> structures such as for loops using monads. it's my own lib: -- |Conditional execution whenM cond action = do allow <- cond when allow action -- |Execute `action` only on (Just ...) value, returned by `x` whenJustM x action = x >>= maybe (return Nothing) action -- |Repeat forever repeat_foreverM action = do action repeat_foreverM action -- |Control structure like to `while` in Pascal repeat_whileM inp cond out = do x <- inp if (cond x) then do out x repeat_whileM inp cond out else return x -- |Control structure like to `repeat-until` in Pascal repeat_untilM action = do done <- action when (not done) $ do repeat_untilM action -- |Execute `action` on `x`, then on each element of list, returned by `action` and further recursively recursiveM action x = action x >>= mapM_ (recursiveM action) -- |Execute `action` recursively if `cond` is true and only on `x` otherwise recursiveIfM cond action x = if cond then recursiveM action x else (action x >> return ()) i also like to use mapM to iterate over lists: xs_processed <- (`mapM` xs) $ \x -> do -- some code using `x` return ... -- Best regards, Bulat mailto:bulatz@HotPOP.com