{- import/export -}
module Export( List(..), Bool( False, True )
             , fromTo, foldr, foldl, foldlStrict
             , addint, mulint, ltint, main ) where

instruction primadd "addint" :: Int! -> Int! -> Int!
instruction primmul "mulint" :: Int! -> Int! -> Int!
instruction primlt  "ltint" :: Int! -> Int! -> Bool!
instruction primle  "leint" :: Int! -> Int! -> Bool!

data Bool   = False | True
data List a = Nil | Cons a (List a)


ltint  x y = let! x = x in let! y = y in primlt x y
leint  x y = let! x = x in let! y = y in primle x y
addint x y = let! x = x in let! y = y in primadd x y
mulint x y = let! x = x in let! y = y in primmul x y

main
  = 42

fromTo :: Int -> Int -> List Int
fromTo n m
  = case leint n m of
      True  -> let! n1 = addint n 1 in Cons n (fromTo n1 m)
      False -> Nil

foldr :: (a -> b -> b) -> b -> List a -> List b
foldr f z xs
  = case xs of
      Nil       -> z
      Cons x xx -> f x (foldr f z xx)

foldl f z xs
  = case xs of
      Nil       -> z
      Cons x xx -> foldl f (f z x) xx

foldlStrict f z xs
  = case xs of
      Nil       -> z
      Cons x xx -> let! y = f z x in foldlStrict f y xx