{-# LANGUAGE CPP, DeriveDataTypeable #-} -- | -- Module : Data.Text.Internal.Functions -- Copyright : 2010 Bryan O'Sullivan -- -- License : BSD-style -- Maintainer : bos@serpentine.com -- Stability : experimental -- Portability : GHC -- -- /Warning/: this is an internal module, and does not have a stable -- API or name. Functions in this module may not check or enforce -- preconditions expected by public modules. Use at your own risk! -- -- Useful functions. module Data.Text.Internal.Functions ( intersperse ) where -- | A lazier version of Data.List.intersperse. The other version -- causes space leaks! intersperse :: a -> [a] -> [a] intersperse :: a -> [a] -> [a] intersperse a _ [] = [] intersperse a sep (a x:[a] xs) = a x a -> [a] -> [a] forall a. a -> [a] -> [a] : [a] -> [a] go [a] xs where go :: [a] -> [a] go [] = [] go (a y:[a] ys) = a sep a -> [a] -> [a] forall a. a -> [a] -> [a] : a ya -> [a] -> [a] forall a. a -> [a] -> [a] : [a] -> [a] go [a] ys {-# INLINE intersperse #-}