Proposal: Add (&) to Data.Function
Milan Straka
fox at ucw.cz
Wed Nov 21 15:08:08 CET 2012
Hi all,
+1 for (&), -1 for (|>).
Cheers,
Milan
> It is a common idiom to write a sequence of composed combinators in
> reverse order to the way they would be written with ($) or (.). That
> naturally expresses the idea of the combinators as operations being
> applied in the given order.
>
> This comes up so often, and is commonly used so many times in a single
> expression, that Control.Arrow.>>> is far too wordy, and even a two-
> character operator is awkward.
>
> Surprisingly, until recently the operator (&) was still not used in any
> of the popular libraries, and its name naturally expresses the idea we are
> looking for. This operator has now been defined in the lens package. We
> hereby propose to move it to its natural home for more general use,
> Data.Function.
>
> As in the lens package, we define the operator as a flipped version of
> ($), but with slightly higher precedence for better interaction with
> ($), and with left associativity. This definition has already proven
> useful and convenient even in the presence of the large and varied corpus
> of combinators and operators in the lens package. (There it was formerly
> known as (%), but that clashed with the usual meaning of (%) from
> Data.Ratio.)
>
> infixl 1 &
> (&) :: a -> (a -> b) -> b
> a & f = f a
> {-# INLINE (&) #-}
>
> Discussion period: 2 weeks
>
> http://hackage.haskell.org/trac/ghc/ticket/7434
>
> Thanks,
> Yitz
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