{- import/export -}
module Custom( List(..), Bool( False, True )
             , foldlStrict, main ) where

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

main
  = 42

custom typedecl Set : public ["forall a.Set a = List a"]
custom infix (+) : public [5,right]
custom infix (*) : public [6,left]

-- another, "helium" specific, way to do the above
custom helium infix  : public ["infixr 9 (+),(*)"]
custom helium "type" : public ["type Set a = List a"]

foldl f z xs : public [custom "type" ["(b -> a -> b) -> b -> [a] -> [b]"], custom "arity" [3]]
  = 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