Using Network.URI, I find I quite often want to do relative URI calculations on URI strings without explicitly handling URI values. I have a candidate function that might be added to Network.URI, with test cases: [[ -- Create a new URI string that is a supplied local URI relative -- to a given base URI, both supplied as strings. relativeToStr :: String -> String -> Maybe String relativeToStr rel base = do -- in Maybe monad: { b <- parseURIReference base ; r <- parseURIReference rel ; u <- r `relativeTo` b ; return $ (uriToString id u) "" } test_rs1 = ("foo" `relativeToStr ` "zz://auth/base/") == Just "zz://auth/base/foo" test_rs2 = ("abs://a/u" `relativeToStr ` "zz://auth/base/") == Just "abs://a/u" test_rs3 = ("[][]" `relativeToStr ` "zz://auth/base/") == Nothing test_rs4 = ("foo" `relativeToStr ` "[][]") == Nothing test_rs5 = ("foo" `relativeToStr ` "bar") == Just "foo" test_rs = and [test_rs1,test_rs2,test_rs3,test_rs4,test_rs5] ]] (I'm not sure the name is the best possible choice.) Is this kind of helper function useful to add to Network.URI? Maybe also a corresponding: relativeFromStr :: String -> String -> Maybe String ? #g ------------ Graham Klyne For email: http://www.ninebynine.org/#Contact