How to split a string in Haskell?

Question

Is there a standard way to split a string in Haskell?

lines and words work great from splitting on a space or newline, but surely there is a standard way to split on a comma?

I couldn't find it on Hoogle.

To be specific, I'm looking for something where split "," "my,comma,separated,list" returns ["my","comma","separated","list"].

Answer 1

Remember that you can look up the definition of Prelude functions!

http://www.haskell.org/onlinereport/standard-prelude.html

Looking there, the definition of words is,

words   :: String -> [String]
words s =  case dropWhile Char.isSpace s of
                      "" -> []
                      s' -> w : words s''
                            where (w, s'') = break Char.isSpace s'

So, change it for a function that takes a predicate:

wordsWhen     :: (Char -> Bool) -> String -> [String]
wordsWhen p s =  case dropWhile p s of
                      "" -> []
                      s' -> w : wordsWhen p s''
                            where (w, s'') = break p s'

Then call it with whatever predicate you want!

main = print $ wordsWhen (==',') "break,this,string,at,commas"