{-# LANGUAGE CPP #-} {-# LANGUAGE Safe #-} {- | Copyright: (c) 2016 Stephen Diehl (c) 20016-2018 Serokell (c) 2018 Kowainik License: MIT Maintainer: Kowainik <xrom.xkov@gmail.com> This module contains useful functions to work with 'Functor' type class. -} module Relude.Functor.Fmap ( (<<$>>) , (<&>) , flap , (??) ) where import Relude.Function ((.)) import Relude.Functor.Reexport (Functor (..)) import Data.Functor ((<$>)) #if MIN_VERSION_base(4,11,0) import Data.Functor ((<&>)) #else -- | Flipped version of '<$>'. infixl 1 <&> (<&>) :: Functor f => f a -> (a -> b) -> f b as <&> f = f <$> as {-# INLINE (<&>) #-} #endif -- $setup -- >>> import Relude.Base (negate, (*), (+)) -- >>> import Relude.Monad (Maybe (..)) -- >>> import Relude.List ((++)) {- | Alias for @fmap . fmap@. Convenient to work with two nested 'Functor's. >>> negate <<$>> Just [1,2,3] Just [-1,-2,-3] -} infixl 4 <<$>> (<<$>>) :: (Functor f, Functor g) => (a -> b) -> f (g a) -> f (g b) (<<$>>) = fmap . fmap {-# INLINE (<<$>>) #-} {- | Takes a function in a 'Functor' context and applies it to a normal value. >>> flap (++) "relude" "P" "Prelude" -} flap :: Functor f => f (a -> b) -> a -> f b flap ff x = (\f -> f x) <$> ff {-# INLINE flap #-} {- | Operator version of the 'flap' function. >>> [(+2), (*3)] ?? 5 [7,15] >>> Just (+3) ?? 5 Just 8 -} infixl 4 ?? (??) :: Functor f => f (a -> b) -> a -> f b (??) = flap {-# INLINE (??) #-}