Hi, I'm writing a parser where I find myself in need to use manyTill combinator with an additional constraint that there should be at least one meaningful element before the trailer (say, a word ended with a period: 'abc.'). Here is what I have: many1Till :: Parser a -> Parser end -> Parser [a] many1Till p end = do p1 <- p ps <- manyTill p end return (p1:ps) The problem here is that I want to catch and report a case when 'p1' could be actually parsed by 'end' ('..' is not a word ended by a period). Generally 'p' and 'end' can parse the same subset of strings. Another version a had was: many1Till :: Parser a -> Parser end -> Parser [a] many1Till p end = do try (end >> (unexpected "sequence terminator")) <|> (do { p1 <- p; ps <- manyTill p end; return (p1:ps) }) Here there are two disadvantages: 1) I don't like hardcoding "sequence terminator" here; 2) the error output should say that only 'p' parser is expected, while it says (technically correct) that either 'p' or 'end' is expected: Prelude Main Text.ParserCombinators.Parsec> parseTest (many1Till letter (char '.')) "1" parse error at (line 1, column 1): unexpected "1" expecting "." or letter (What I want here is to say "expecting letter") Any suggestions? Thanks! -- Vlad Skvortsov, vss@73rus.com, http://vss.73rus.com