Haskell Language Replacing all elements of a Functor with a single value


Example

The Data.Functor module contains two combinators, <$ and $>, which ignore all of the values contained in a functor, replacing them all with a single constant value.

infixl 4 <$, $>

<$ :: Functor f => a -> f b -> f a
(<$) = fmap . const

$> :: Functor f => f a -> b -> f b
($>) = flip (<$)

void ignores the return value of a computation.

void :: Functor f => f a -> f ()
void = (() <$)