[Haskell-beginners] Defining 'words' in terms of 'span'

[Roger Whittaker]

I found some exam papers linked from this page:
http://www.cs.chalmers.se/Cs/Grundutb/Kurser/d1pt/d1pta/external.html

And I have been trying some questions from them.  

I'm currently baffled by question 2(b) on this one:
http://www.cs.chalmers.se/Cs/Grundutb/Kurser/d1pt/d1pta/tenta2000-04.ps

  A word is a sequence of alphabetic characters, which you can recognise
  using the standard function

  isAlpha :: Char -> Bool

  Using span, define a function words :: String -> [String] which
  finds a list of the words occurring in a string. For example,

  words "Now is the winter of our discontent!"
    == ["Now","is","the","winter","of","our","discontent"]

  words "2+3" == []

  words "1 by 1" == ["by"]

Can anyone give me a clue how to start?




-- 
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Roger Whittaker
roger at disruptive.org.uk
http://disruptive.org.uk
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