[Haskell-cafe] Re: Very crazy
dominic.steinitz at blueyonder.co.uk
Tue Sep 25 07:33:13 EDT 2007
Andrew Coppin <andrewcoppin <at> btinternet.com> writes:
> I just found it rather surprising. Every time *I* try to compose with
> functions of more than 1 argument, the type checker complains.
> Specifically, suppose you have
> foo = f3 . f2 . f1
> Assuming those are all 1-argument functions, it works great. But if f1
> is a *two* argument function (like map is), the type checker refuses to
> allow it, and I have to rewrite it as
> foo x y = f3 $ f2 $ f1 x y
Look at the type of (.).(.) which should tell you how to compose functions
with more than one variable. Mind you, I don't think it improves readability.
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