words package:base

words :: String -> [String]
base Prelude Data.List Data.String GHC.OldList
words breaks a string up into a list of words, which were delimited by white space (as defined by isSpace). This function trims any white spaces at the beginning and at the end. 
>>> words "Lorem ipsum\ndolor"
["Lorem","ipsum","dolor"]

>>> words " foo bar "
["foo","bar"]
unwords :: [String] -> String
base Prelude Data.List Data.String GHC.OldList
unwords joins words with separating spaces (U+0020 SPACE). 
>>> unwords ["Lorem", "ipsum", "dolor"]
"Lorem ipsum dolor"
unwords is neither left nor right inverse of words: 
>>> words (unwords [" "])
[]

>>> unwords (words "foo\nbar")
"foo bar"