-- an idea for splitting fields a la RFC2822.
-- for Haskell Libraries email list 2004-06-08.

module Fieldsplit where

import Char

fieldsplit :: String -> [(String,String)]
fieldsplit s =
  goheader (lines s)
      where goheader [] = []
            goheader ("":ls) = goheader ls  -- in RFC-2822, this marks the end of headers
            goheader (r@(c:_):ls) | isSpace c = error "Missing field header"
                                  | otherwise = case break (== ':') r of
                                                  (h,':':r') -> gobody h ls [r']
                                                  _          -> error "Missing colon"

            gobody h (r@(c:_):ls) rs | isSpace c = gobody h ls (r:rs)
            gobody h ls           rs             = (h, unwords (reverse rs)) : goheader ls