functionmusings.elm

type alias Function a b = a -> b


const : b -> Function a b
const b _ = b 


compose : Function a b -> Function b c -> Function a c
compose = 
  (>>)


map : (a -> b) -> Function x a -> Function x b
map = 
  (<<)
  
  
contramap : (b -> a) -> Function a x -> Function b x
contramap = 
  (>>)
    
  
map2 : (a -> b -> c) -> Function x a -> Function x b -> Function x c
map2 f xa xb x =
  f (xa x) (xb x)
  

andMap : Function x (a -> b) -> Function x a -> Function x b
andMap = 
  map2 (<|)
  
  
flatten : Function x (Function x a) -> Function x a
flatten f x = 
  (f x) x
  
  
flatMap : (a -> Function x b) -> Function x a -> Function x b
flatMap f =
  map f >> flatten
  
  
andThen : Function x a -> (a -> Function x b) -> Function x b
andThen =
  flip flatMap