On 4/14/2014 4:34 AM, Patrick Wheeler wrote:
@John That way you can write code that looks like:
main = do myargs <- getArgs forM_ myargs $ \s -> do putStrLn s putStrLn $ "Second string" ++ s
That still introduces a throw-away name and extracts the args on another line. Is there a way to do something like: main = do forM_ (dereference getArgs) $ \s -> do ... or mforM_ getArgs $ \s -> do ...
You can read the discussion around om: http://www.reddit.com/r/haskell/comments/1i2zmq/a_useful_function_om/
Thanks, I will. I guess it bothers me that "wrapped" values in the IO monad can't be independently used in situ, but need to be given a name on another line first. Isn't the likes of "lift" and (even nicer) <*> supposed to address this idea? I can't quite see why that doesn't work here. (And that begs the question of why getArgs needs to be monadic in the first place. It doesn't change its value; it's a strict constant at run-time, and not knowing it at compile time is my problem how?) —John