parser.hs

import Text.ParserCombinators.Parsec

data Prefix = Prefix String String String deriving Show

data Command = Action String | Code Int deriving Show

data Params = Params [String] deriving Show

data Message = Message (Maybe Prefix) Command Params String deriving Show

prefix :: Parser Prefix
prefix = do
  n <- many1 (noneOf "!")
  char '!' 
  u <- many1 (noneOf "@")
  char '@' 
  h <- many1 (noneOf " ")
  return $ Prefix n u h 

stripNick :: String -> String
stripNick s = if head s `elem` "@~!&" then tail s else s

command :: Parser Command
command = action <|> code

action :: Parser Command
action = many1 upper >>= return . Action

code :: Parser Command
code = do
  x <- digit
  y <- digit
  z <- digit
  return $ Code $ read [x,y,z]

params :: Parser Params
params = fmap Params $ many1 (noneOf ":") `sepBy` spaces

message :: Parser Message
message = do
  optional $ char ':' 
  p <- optionMaybe prefix
  c <- command
  ps <- params
  optional $ char ':' 
  m <- many (noneOf "\r\n")
  string "\r\n"
  return $ Message p c ps m

> :l parser.hs 
[1 of 1] Compiling Main             ( parser.hs, interpreted )
Ok, modules loaded: Main.
> let parseIRC = \s -> either (\_ -> error "fak") (\b -> b) (parse message "irc" s)
> parseIRC ":CalebDelnay!calebd@localhost PRIVMSG #mychannel :Hello everyone!\r\n"
*** Exception: fak
>