hPutBuf is expensive, need a better alternative/implementation for faster fileio

[harendra-kumar]

See this example . If we compare the C printf with our print statement using hPutBuf it performs poorly.

    printName arr off = do
        -- If we use an Array then we can use a slice of the same
        -- buffer for printing and for passing to loopDir.
        MutByteArray.pokeAt off arr (10 :: Word8)
        -- hPutBuf is quite expensive compared to C printf.
        -- There should be an API that supplies the buffer directly to kernel.
        -- And we can build a buffer in the loop here and write it when it is
        -- ready.
        MutByteArray.unsafeAsPtr arr $ \p ->
            hPutBuf stdout p (off+1)

This matters only if we use it too often for small data printing. This is a common case for routine printing on console.