Add `drop` to `Text.Megaparsec`

[sol]

I'd love to have Text.Megaparsec to export

-- | Advance by / ignore `n` input tokens
drop :: MonadParsec e s m => Int -> m ()
drop n = P.skipCount n $ P.token Just mempty

(or possibly implement it with getOffset / setOffset, if that results in the exact same parser state, not sure)

[mrkkrp]

IIUC you want this as a new primitive? (Because there is already skipCount in parser-combinators.)

[sol]

I think skipCount requires a parser as an argument, whereas I want to unconditionally drop / ignore a specified number of tokens.

[mrkkrp]

I think now mkParsec can now be used to implement any primitive, including what you propose here. I think it would even make sense to re-implement some of the methods of MonadParsec in terms of mkParsec and thus reduce the number of methods of that class :thinking: