Dear Haskellers! Another letter from newbie :) May you criticize my code for replacing substring in a string cited below? Any critics and comments are highly appreciated. And some more questions: 1. Is there more functional way for text processing? For example, intuitively I feel that there is more functional approach for matching than one suggested below. 2. Is there a kind of book simlar to "Text processing with Python?". 3. I found several regular exprssions library for Haskell. Which one would you recommend for *learning*---I am not too interested in performance by now, but rather in exampels of good Haskell. 4. What Haskell sources (snippets, modules, etc) can you recommend as examples of good Haskell. Replace: data Match = None | Rest String deriving Show match :: String -> String -> Match match pattern s = case match_ pattern s of ("", rest) -> Rest rest _ -> None where match_ :: String -> String -> (String, String) match_ pattern@(p:ps) str@(s:ss) = if p == s then match_ ps ss else (pattern, str) match_ pattern s = (pattern, s) findAll :: String ->String -> (String -> String) -> String findAll pattern = findAll_ where findAll_ :: String -> (String -> String) -> String findAll_ "" _ = "" findAll_ s@(head:tail) f = case match pattern s of Rest rest -> (f pattern) ++ findAll_ rest f None -> head:findAll_ tail f replace :: String -> String -> String -> String replace _ "" _ = "" replace what s to = case match what s of Rest rest -> to ++ replace what rest to None -> (head s):(replace what (tail s) to) replace3 what s to = findAll what s (\_ -> to) Notes: It seems that Match may be better written with Maybe. is there any pros & contros? Which version of replace would you prefer and why? Is it effecient enough or there are better ways? I beg your pardon for such a long letter. -- Best regards, antonmuhin mailto:antonmuhin@rambler.ru