26 Sep
2011
26 Sep
'11
12:49 p.m.
Evan Laforge wrote:
hex2 = (+)<$> ((*16)<$> higit)<*> higit higit = subtract (fromEnum '0')<$> satisfy isHexDigit color = Color<$> hex2<*> hex2<*> hex2
Twan van Laarhoven wrote:
How is "subtract (fromEnum '0')" supposed to convert a hex digit to an Int or Word8? I think you need digitToInt (or an equivalent function) for that.
Right. How about: color = Color <$> hex2 <*> hex2 <*> hex2 hex2 = mkHex2 <$> hexit <*> hexit hexit = satisfy isHexDigit mkHex2 h1 h0 = fst . head $ readHex [h1, h0] Or, if you are fanatic about safety like I am, you might even write: mkHex2 h1 h0 = maybe 0 fst . listToMaybe $ readHex [h1, h0] Regards, Yitz