Statically typed stack language. http://evincarofautumn.blogspot.com/2012/02/why-concatenative-programming-matters.html

concatenative.hs

{-# LANGUAGE RankNTypes #-}


(!) = flip (.)

lit :: a -> s -> (s, a)
lit x s = (s, x)

run :: (forall a. a -> (a, b)) -> b
run x = snd $ x undefined

lift1 :: (a -> b) -> (s, a) -> (s, b)
lift1 f = \(s, a) -> (s, f a)

lift2 :: (a -> b -> c) -> ((s, a), b) -> (s, c)
lift2 f = \((s, a), b) -> (s, f a b)

plus :: Num a => ((s, a), a) -> (s, a)
-- plus ((s, a), b) = (s, a + b)
plus = lift2 (+)

ap1 :: ((s, a), a -> b) -> (s, b)
ap1 ((s, a), f) = (s, f a)

ap2 :: (((s, a), b), a -> b -> c) -> (s, c)
ap2 (((s, a), b), f) = (s, f a b)

dup :: (s, a) -> ((s, a), a)
dup (s, a) = ((s, a), a)

swap :: ((s, a), b) -> ((s, b), a)
swap ((s, a), b) = ((s, b), a)

drop' :: (s, a) -> s
drop' = fst