bit-matching

How to install the language extension

Install the package via raco or the package manager in DrRacket.

raco pkg install https://github.com/capfredf/bit-matching.git

and then

#lang bit-matching

How to construct a bit-string

<e1 ... en>

Each ei is a semgment of a bit string. It is a pair of (expr size). expr must be evaluated to a number and currently size must be a literal numbe and it indicates the number of bits in which the value of expr will be encoded.

(define a <(1 4)(1 4)>)
;; a => (bytes 17) or (bytes #b00010001)

How to extract segments of bit-string

(bit-match expr
 (<seg-pat-1 ... seg-pat-n> body))

The function bit-match is similar to match, except that it only works for bit-strings. Each seg-pat-i is a pattern against a semgment of a bit string. It is a pair of (val-pattern size-pat). val-pattern can be either identifier or literal number. When it is a bound identifier, the bit-match will use the value to match against the value of expr. When it is unbound and the matching succeeds, it will be assigned to the value decoded in the number of bits specified by size-pat. size-pat must be a literal number.

Future work

see Issues