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{-# LANGUAGE MultiParamTypeClasses, FunctionalDependencies, FlexibleInstances, TypeSynonymInstances, OverlappingInstances #-} {-# OPTIONS_GHC -Wall #-} ------------------------------------------------------------------------------- {- | Module : Data.Stream Description : Streams of values. Copyright : (c) Paulo Silva License : LGPL Maintainer : paufil@di.uminho.pt Stability : experimental Portability : portable -} ------------------------------------------------------------------------------- module Data.Stream where ------------------------------------------------------------------------------- class Stream a v | a -> v where headStr :: a -> v tailStr :: a -> a ------------------------------------------------------------------------------- instance Stream [a] a where headStr = head tailStr = tail ------------------------------------------------------------------------------- instance Stream Int Int where headStr n = n tailStr n = succ n ------------------------------------------------------------------------------- instance Stream [String] String where headStr = head tailStr = tail ------------------------------------------------------------------------------- |