module Datacon0 (llen) where

import Language.Haskell.Liquid.Prelude

data Foo a = F a a a 

data LL a = N | C a (LL a)

{-@ data LL [llen] @-} 


{-@ measure llen @-}
llen :: LL a -> Int 
{-@ llen :: LL a -> Nat @-}
llen N = 0 
llen (C _ xs) = 1 + llen xs 

lmap f N = N
lmap f (C x xs) = C (f x) (lmap f xs)

range :: Int -> Int -> LL Int
range i j = C i N

n = choose 0

prop_rng1 = (liquidAssertB . (0 <=)) `lmap` range 0 n

--poo :: LL Int
poo = C (1 :: Int)