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

[Ozgur Akgun]

You might start with looking into
span<http://haskell.org/ghc/docs/latest/html/libraries/base-4.2.0.0/Prelude.html#v:span>
.

span :: (a -> Bool) -> [a] -> ([a], [a])


For example try these,

span ('a'==) "abcd"
span ('a'==) "aaabcd"
span ('c'==) "abcd"
span ('c'/=) "abcd"
span ('c'/=) "abcdcdcd"



On 16 March 2010 17:08, Roger Whittaker <roger at disruptive.org.uk> wrote:

> 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?
>
>
>
>
> --
> ========================
> Roger Whittaker
> roger at disruptive.org.uk
> http://disruptive.org.uk
> ========================
> _______________________________________________
> Beginners mailing list
> Beginners at haskell.org
> http://www.haskell.org/mailman/listinfo/beginners
>



-- 
Ozgur Akgun
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://www.haskell.org/pipermail/beginners/attachments/20100316/f92173f7/attachment.html