lookAhead and bytesRead

[td202]

While lookAhead does not consume the input, it does update the bytesRead.

test = do
    x <- bytesRead
    _ <- lookAhead getInt64be
    y <- bytesRead
    return (x, y)

> runGet test (encode (2 :: Int)) -- result: Right (0, 8)

I suspect this is not the desired behaviour, and that the above example should return (0, 0), to reflect that no bytes of the input have been consumed. If this is the desired behaviour, it should probably be documented.

[elliottt]

This seems like a bug to me, good find!

[jmazon]

Seems to me it's all the less likely to be the desired behavior that the same code does return (0,0) when run against binary.