toByteString package:blaze-builder

Run the builder to construct a strict bytestring containing the sequence of bytes denoted by the builder. This is done by first serializing to a lazy bytestring and then packing its chunks to a appropriately sized strict bytestring.

toByteString = packChunks . toLazyByteString

Note that toByteString is a Monoid homomorphism.

toByteString mempty          == mempty
toByteString (x `mappend` y) == toByteString x `mappend` toByteString y

However, in the second equation, the left-hand-side is generally faster to execute.

toByteStringIOWith bufSize io b runs the builder b with a buffer of at least the size bufSize and executes the IO action io whenever the buffer is full. Compared to toLazyByteStringWith this function requires less allocation, as the output buffer is only allocated once at the start of the serialization and whenever something bigger than the current buffer size has to be copied into the buffer, which should happen very seldomly for the default buffer size of 32kb. Hence, the pressure on the garbage collector is reduced, which can be an advantage when building long sequences of bytes.

Run a Write to produce a strict ByteString. This is equivalent to (toByteString . fromWrite), but is more efficient because it uses just one appropriately-sized buffer.