[Haskell-beginners] applicative style
Brandon Allbery
allbery.b at gmail.com
Fri Aug 28 17:23:10 UTC 2015
On Fri, Aug 28, 2015 at 1:12 PM, Williams, Wes(AWF) <wewilliams at paypal.com>
wrote:
> Num (Int -> Maybe a -> r))
That looks highly suspect. If it infers a function Num instance, you
probably got your parentheses wrong. Or your $-s...
...in fact, that is the problem. That final $ does not do what you think;
it produces
(foldl (+) 0 estimates <*> Just . fromIntegral) (length estimates)
when you presumably intended
foldl (+) 0 estimates <+> (Just . fromIntegral) (length estimates)
--
brandon s allbery kf8nh sine nomine associates
allbery.b at gmail.com ballbery at sinenomine.net
unix, openafs, kerberos, infrastructure, xmonad http://sinenomine.net
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