Re: [Haskell-cafe] Point-free style

At 09:00 11/02/05 +0100, Ketil Malde wrote:

Matthew Roberts writes:

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[Point-free] compositions of functions with arity greater than 1, [...] compositions of sections of composition or application, arrow notation without the sugar, and so forth---will always be more difficult to read and understand than the direct version.

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I have to agree (although I suspect few others will :))

I tend to agree, also. Type signatures help, of course. E.g. with the previously mentioned and rather cryptic function

(.) . (.) .(.)

I entered it into GHCi, and got

:: forall a a b c a. (b -> c) -> (a -> a -> a -> b) -> a -> a -> a -> c

and it suddenly is much clearer what it does.

Hmm... noting the discrepancy with HUGS mentioned later in this thread, I entered this into GHCi and got this: [[ Prelude> :t (.) . (.) . (.) (.) . (.) . (.) :: forall a a1 b c a2. (b -> c) -> (a -> a1 -> a2 -> b) -> a -> a1 -> a2 -> c ]] I think you maybe dropped the digits in the type variable names? #g ------------ Graham Klyne For email: http://www.ninebynine.org/#Contact