A BitBuilder is an efficient way to build lazy ByteStrings. There are several functions for constructing BitBuilders, but only one to inspect them: to extract any data, you have to turn them into lazy ByteStrings using toLazyByteString.

Internally, a BitBuilder constructs a lazy Bytestring by filling byte arrays piece by piece. As each buffer is filled, it is 'popped' off, to become a new chunk of the resulting lazy ByteString. All this is hidden from the user of the BitBuilder.

This is closely based on the Builder monad, but this one deals with single bits at a time.

O(n). Extract a lazy ByteString from a BitBuilder. The construction work takes place if and when the relevant part of the lazy ByteString is demanded.

O(1). The empty BitBuilder, satisfying

• toLazyByteString empty = empty

O(1). A BitBuilder taking a single bit, satisfying

• toLazyByteString (singleton b) = singleton b

O(1). The concatenation of two BitBuilders, an associative operation with identity empty, satisfying

• toLazyByteString (append x y) = append (toLazyByteString x) (toLazyByteString y)

O(1). A BitBuilder taking a lazy ByteString, satisfying

• toLazyByteString (fromLazyByteString bs) = bs

Construct a BitBuilder by taking the bottom n bits of a Bits instance. If the instance has less than n bits, this acts as if there was an infinite zero filled prefix

O(1). Pop the ByteString we have constructed so far, if any, yielding a new chunk in the result lazy ByteString.