preserves/quoting.rkt

104 lines
3.9 KiB
Racket

#lang racket
(require racket/trace)
(struct DISCARD ())
(struct CAPTURE (p))
(define (q p)
(match p
[(DISCARD) `(discard)]
[(CAPTURE p) `(capture ,(q p))]
[`(discard) `('discard)]
[`(capture ,p) `('capture ,(q p))]
[`(quote ,p) `('quote ,(q p))]
[`(,pa . ,pd) `(,(q pa) . ,(q pd))]
[a a]))
(define (uq p)
(match p
[`(discard) (DISCARD)]
[`(capture ,p) (CAPTURE (uq p))]
[`(quote ,p) p]
[`(,pa . ,pd) `(,(uq pa) . ,(uq pd))]
[a a]))
;; Goal: (uq (q p)) === p
;; (define (m p v k)
;; (match* (p v)
;; [(`(discard) _) (k '())]
;; [(`(capture ,p) v) (m p v (lambda (bs) (cons v bs)))]
;; [(`(quote ,p) v) (and (equal? p v) (k '()))]
;; [(`(,pa . ,pd) `(,va . ,vd)) (m pa va (lambda (bs) (m pd vd (lambda (cs) (k (append bs cs))))))]
;; [(p v) (and (equal? p v) (k '()))]))
(define (m p v k)
(match* (p v)
[((DISCARD) _) (k '())]
[((CAPTURE p) v) (m p v (lambda (bs) (cons v bs)))]
[(`(,pa . ,pd) `(,va . ,vd)) (m pa va (lambda (bs) (m pd vd (lambda (cs) (k (append bs cs))))))]
[(p v) (and (equal? p v) (k '()))]))
;; (trace m)
(module+ test
(require rackunit)
;; (define (M p v) (m p v values))
(define (M p v) (m (uq p) v values))
(check-equal? (M `(capture 1) 1) '(1))
(check-equal? (M `(discard) 1) '())
(check-equal? (M 1 1) '())
(check-equal? (M 2 1) #f)
(check-equal? (M `(capture 2) 1) #f)
(check-equal? (M `(record (capture (discard))) `(record value)) '(value))
(check-equal? (M `(record (capture (discard))) `(record 'value)) '('value))
(check-equal? (M `(record (capture (discard))) `(record (capture (discard))))
'((capture (discard))))
(check-equal? (M `(record ('capture (discard))) `(record (capture (discard))))
'())
(check-equal? (M `(record (capture ('capture (discard)))) `(record (capture (discard))))
'((capture (discard))))
(check-equal? (M `(record (capture ('capture (discard)))) `(record value))
#f)
(check-equal? (M `(record (capture ('capture (discard)))) `(record 'value))
#f)
(check-equal? (M `(record (capture ('capture (discard)))) `(record ('capture (discard))))
#f)
(check-equal? (M `(record '(capture (discard))) `(record (capture (discard))))
'())
(check-equal? (M `(record (capture '(capture (discard)))) `(record (capture (discard))))
'((capture (discard))))
(check-equal? (M `(record (capture '(capture (discard)))) `(record value))
#f)
(check-equal? (M `(record (capture '(capture (discard)))) `(record 'value))
#f)
(check-equal? (M `(record (capture '(capture (discard)))) `(record '(capture (discard))))
#f)
(check-equal? (M `(record ('quote value)) `(record (capture (discard)))) #f)
(check-equal? (M `(record (capture ('quote value))) `(record (capture (discard)))) #f)
(check-equal? (M `(record (capture ('quote value))) `(record value)) #f)
(check-equal? (M `(record (capture ('quote value))) `(record 'value)) '('value))
(check-equal? (M `(record (capture ('quote value))) `(record 'notvalue)) #f)
(check-equal? (M `(record ('quote value)) `(record 'value)) '())
(check-equal? (M `(record (capture ('quote value))) `(record ('quote value))) #f)
(check-equal? (M `(record ''value) `(record (capture (discard)))) #f)
(check-equal? (M `(record (capture ''value)) `(record (capture (discard)))) #f)
(check-equal? (M `(record (capture ''value)) `(record value)) #f)
(check-equal? (M `(record (capture ''value)) `(record 'value)) '('value))
(check-equal? (M `(record (capture ''value)) `(record 'notvalue)) #f)
(check-equal? (M `(record ''value) `(record 'value)) '())
(check-equal? (M `(record (capture ''value)) `(record ''value)) #f)
(check-equal? (q (CAPTURE 1)) `(capture 1))
(check-equal? (q (DISCARD)) `(discard))
(check-equal? (q `(capture 1)) `('capture 1))
(check-equal? (q `(discard)) `('discard))
)