'scan' doesn't progress cursor.

[xOC4]

Cursor doesn't get advanced input upon successful state predicate match.

So the following will enter an infinite loop instead of parsing the lead "ABCD"
parseBytes (scan 0x41 (\b w -> if b <= w then Just w else Nothing)) (fromString "ABCDABCD")

Possible change:

let go s = do
        mw <- peek
        case mw of
          Nothing -> pure s
          Just w -> case t s w of
            Just s' -> anyUnsafe >> go s'
            Nothing -> pure s'

[andrewthad]

I will accept a PR that fixes this if anyone opens one.