& package:ghc-internal
& is a reverse application operator. This provides
notational convenience. Its precedence is one higher than that of the
forward application operator
$, which allows
& to be
nested in
$.
This is a version of
flip id, where
id
is specialized from
a -> a to
(a -> b) -> (a
-> b) which by the associativity of
(->) is
(a
-> b) -> a -> b. flipping this yields
a -> (a
-> b) -> b which is the type signature of
&
Examples
>>> 5 & (+1) & show
"6"
>>> sqrt $ [1 / n^2 | n <- [1..1000]] & sum & (*6)
3.1406380562059946
Boolean "and", lazy in the second argument
Fanout: send the input to both argument arrows and combine their
output.
The default definition may be overridden with a more efficient version
if desired.
╭───────╮ c
b │ ┌─ f ─┼───>
>───┼─┤ │
│ └─ g ─┼───>
╰───────╯ c'
Flipped version of
<$>.
(<&>) = flip fmap
Examples
Apply
(+1) to a list, a
Just and a
Right:
>>> Just 2 <&> (+1)
Just 3
>>> [1,2,3] <&> (+1)
[2,3,4]
>>> Right 3 <&> (+1)
Right 4