NAry.hs

NAry.hs

fmap2 :: (Functor f1, Functor f2) => (a -> b) -> f1 (f2 a) -> f1 (f2 b)
fmap2 = fmap . fmap

for :: Functor f => f a -> (a -> b) -> f b
for = flip fmap

infixr $:
($:) :: (Functor f, Functor g) => f (g a) -> (a -> b) -> f (g b)
($:) = flip fmap2

infixr $*
($*) :: Functor f => f a -> (b -> c) -> (a -> b) -> f c
f $* g = for f $: g

infixr $$
($$) :: (Functor f, Functor g) => f a -> g b -> (a -> b -> c) -> f (g c)
f $$ g = for f $: for g

x = ((+1) $* (*4) $* id $* (+10) $$ const 1) (,,,,) 0 3 'A' 7 2
-- x = (1,12,'A',17,1)

y = ((+1) $* (+2) $* (+3) $* (\(x,y,z) -> x+y+z)) (,,) 0 0 0
-- y = 6