id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc	os	architecture	failure	difficulty	testcase	blockedby	blocking	related
7434	Add (&) to Data.Function	YitzGale		"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 (&) #-}
}}}"	feature request	closed	normal		libraries/base	7.6.1	wontfix		pho@…	Unknown/Multiple	Unknown/Multiple	None/Unknown	Unknown