bitmatch syntax

(use srfi-1)

(define-syntax bit-syntax
  (syntax-rules (match)
    ((_ x) `((rest ,x)))
    ((_ x (match n l) z ...)
     (let-values (((left right) (split-at x l)))
       (cons (cons (quote n) left)
             (bit-syntax right z ...))))
    ((_ x y z ...) (and (= (car x) y) `(rest ,(cdr x))
                        (bit-syntax (cdr x) z ...)))))


;; input
(bit-syntax '(0 1 2 4 5 6 7) (match x 1) 1 2 (match y 2))

;; output
((x 0) (y 4 5) (rest (6 7)))