Main.purs

module Main where

import Prelude
import Data.Maybe (Maybe)
import Data.List (List)
import Control.Monad.Eff.Console (print)
import Control.Comonad.Cofree (Cofree, mkCofree, head, tail)
import Control.Alternative (class Alternative)
import Control.Plus (empty)

replicate :: forall f a. (Alternative f) => Int -> a -> Cofree f a
replicate 1 a = mkCofree a empty
replicate n a = mkCofree a $ pure (replicate (n-1) a)

class Show1 (f :: * -> *) where
  show1 :: forall a. Show a => f a -> String

instance show1array :: Show1 Array where
  show1 = show

instance show1maybe :: Show1 Maybe where
  show1 = show

instance show1list :: Show1 List where
  show1 = show

newtype C f a = C (Cofree f a)

instance showC :: (Show1 f, Show a, Functor f) => Show (C f a) where
  show (C cofree) =
    "(" <> show (head cofree) <> ") :< (" <> show1 (map C (tail cofree)) <> ")"

x :: forall f. (Alternative f) => C f Char
x = C (replicate 4 'X')

main = do
  print "hi"
  print (x :: C Array Char)
  print (x :: C Maybe Char)
  print (x :: C List Char)