Re: [Haskell-beginners] applicative style

David Moberg writes:

This mail got stuck in my spam filter because of auth reason. Bumping in case someone else who missed it wants to answer.

2015-08-28 19:12 GMT+02:00 Williams, Wes(AWF) :

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Hi haskellers,

I am trying to understand why I get the following error in learning applicative style.

Prelude> let estimates = [5,5,8,8,2,1,5,2]

Prelude> (/) <$> Just $ foldl (+) 0 estimates <*> Just . fromIntegral $ length estimates

I think $ is the culprit. You can not combine $ and <*> and get what you expect, because $ works on *the whole* expression: Prelude> (/) <$> Just (foldl (+) 0 estimates) <*> Just (fromIntegral (length estimates)) Just 4.5 Another problem was (.), you actually don't need any function composition here. -- CYa, ⡍⠁⠗⠊⠕