[Haskell-cafe] Re: [Haskell-beginners] map question
wren ng thornton
wren at freegeek.org
Wed Oct 21 01:17:21 EDT 2009
minh thu wrote:
> Something I wonder from time to time if it would be a good thing or
> not is to allow
> a `f g` b
> to mean
> f g a b
This comes up from time to time, though it is often met with stern
disapproval because it can easily lead to loss of clarity. There is a
valid alternative, though it's not quite as pretty:
($a) (f g...) b c... == f g... a b c...
With even less prettiness, this can also be generalized for other
numbers of prefix arguments:
( ($a) f) b c... == f a b c...
( ($b) $($a) f) c d... == f a b c d...
(($c) $($b) $($a) f) d e... == f a b c d e...
And if anyone wanted to use this sort of pattern frequently, I'm sure
there's some decent way to clean it up ala Matt Hellige's pointless
trick or ala Oleg's polyvariadic trick.
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