Functional Manipulation of Bit Streams

Writing code that manipulates bit streams is a painful and errorprone programming task, currently often performed via bit twiddling techniques such as explicit bit shifts and bit masks in programmer-allocated buffers. Still, this kind of programming is necessary in many application areas ranging from decoding streaming media files to implementing network protocols. In this paper we show how high-level constructs from functional programming, such as binary pattern matching at the bit level and binary comprehensions, can make bit stream manipulation more succinct, less error-prone, and totally memory-safe. We formally define these language constructs, show a variety of example uses from several different application areas, and describe their implementation in detail. We hold that a binary data structure with the ability to perform pattern matching at the bit level allows (purely) functional languages to significantly expand the range of their practical uses.