Wren, I notice that readDecimal has a typesig: readDecimal :: Integral a => ByteString -> Maybe (a, ByteString) which I would then use in Warp as: readInt64BSL :: ByteString -> Int64 readInt64BSL bs = fst $ fromMaybe (0, "") $ BSL.readDecimal bs However, this version with the fromMaybe and fst is a little slower than if these two extra bits weren't necessary. Would you consider a function with the following signature in bytestring-lexing? readDecimalX :: Integral a => ByteString -> a The idea is that it gives something faster for applications like Warp where reading an valid decimal should be as fast as possible, but if the string isn't valid it doesn't really matter what the result is. Cheers, Erik -- ---------------------------------------------------------------------- Erik de Castro Lopo http://www.mega-nerd.com/