Why hide ensure?

Edward Wang avatarEdward Wang created an issue

In this commit:

https:bitbucket.org/bos/attoparsec/changeset/fa4ee945eb21

you hide the ensure function. Can you elaborate a little bit? I find myself in need of it. A binary file I want to parse starts with three 4-byte magics, one of them is length of the file:

parseMagics :: Parser ()
parseMagics = do
    _ <- string "FOR1"
    len <- big_endians 4
    _ <- string "BEAM"
    return $ ensure len

big_endians :: Int -> Parser Int
big_endians n = do
    ws <- count n anyWord8
    return $ foldl1 (\a b -> a * 256 + b) $ map fromIntegral ws

You see, ensure turns out to be very useful under such circumstances.

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