[Haskell-beginners] f . g or f g or f $ g?
poczta at emanuelkoczwara.pl
Fri Feb 1 21:04:13 CET 2013
Dnia 2013-02-01, pią o godzinie 20:42 +0100, Martin Drautzburg pisze:
> Hello all
> I frequently get confused over f . g vs f g. I do understand the following
> g :: a->b
> f :: b ->c
> f.g :: a->c
> f g
> is a type error, because then f would have to accept a function (a->b) as its
> first parameter, but it only accepts a b.
> Is there a way to easily remember when to use f.g and when to use f g without
> having to do this type algebra.
Maybe this could be a hint, consider this:
f . g == (.) f g
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