bosu

{-# LANGUAGE TemplateHaskell #-}
import Pipes
import qualified Pipes.Prelude as P
import MVC
import MVC.Prelude
import Control.Lens

data V = Twice Int | Thrice Int

makePrisms ''V

bosu

{-# LANGUAGE DeriveFunctor, FlexibleInstances #-}
{-# OPTIONS -Wall #-}
import Control.Monad.Free
import Control.Applicative

data SomeF f a = Many [a] | One (f a) deriving Functor

instance Functor f => Alternative (Free (SomeF f)) where
    empty = Free (Many [])