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scopes

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This commit is contained in:
Matthew Butterick 2016-05-13 22:54:54 -07:00
parent 12f8b3d0a5
commit cdda2224da
2 changed files with 108 additions and 41 deletions
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43
beautiful-racket-lib/br/syntax-scopes-test.rkt Normal file
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@ -0,0 +1,43 @@
#lang br
(require (for-syntax br/syntax sugar/debug) br/syntax)
(begin-for-syntax
(define-scope blue)
(define-scope yellow)
(define-scope red)
(define-scope green (blue yellow))
(define-scope purple (blue red)))
(define #'(define-blue _id _val)
(with-blue-binding-form ([x '_id])
#'(define x _val)))
#;(define-blue x (+ 42 42))
(define #'(def-x)
(with-blue-binding-form ([x 'x])
#'(define x (+ 42 42))))
(define #'(def-x-2)
(with-yellow-binding-form ([x 'x])
#'(define x (+ 42))))
(define #'(print-x)
(with-yellow-syntax ([x 'x])
#'(println (+ x x))))
(define #'(print-x-2)
(with-purple-syntax ([x 'x])
#'(println (+ x x x))))
(scopes (syntax-find (expand-once #'(def-x)) 'x))
(def-x)
(def-x-2)
(scopes (syntax-find (expand-once #'(print-x)) 'x))
(print-x)
(scopes (syntax-find (expand-once #'(print-x-2)) 'x))
(print-x-2)
#;(let-syntax ([x (λ(stx) (syntax-case stx () [_ #'42]))])
(* x 4))

106
beautiful-racket-lib/br/syntax.rkt
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@ -58,6 +58,20 @@
(for/list ([scope (in-list (context stx))])
scope))))
(define (syntax-find stx stx-or-datum)
(unless (syntax? stx)
(raise-argument-error 'syntax-find "not given syntax object as first argument" stx))
(define datum
(cond [(syntax? stx-or-datum) (syntax->datum stx-or-datum)]
[(symbol? stx-or-datum) stx-or-datum]
[else (raise-argument-error 'syntax-find "not given syntax or datum as second argument" stx-or-datum)]))
(let/ec exit
(let loop ([so stx])
(cond
[(eq? (syntax->datum so) datum) (exit so)]
[(syntax->list so) => (curry map loop)]))))
(define (->syntax x)
(if (syntax? x) x (datum->syntax #f x)))
@ -70,6 +84,10 @@
(with-syntax ([id-sis (format-id #'id "~a-sis" #'id)]
[add-id (format-id #'id "add-~a" #'id)]
[flip-id (format-id #'id "flip-~a" #'id)]
[id-binding-form (format-id #'id "~a-binding-form" #'id)]
[with-id-syntax (format-id #'id "with-~a-syntax" #'id)]
[let-id-syntax (format-id #'id "let-~a-syntax" #'id)]
[with-id-binding-form (format-id #'id "with-~a-binding-form" #'id)]
[remove-id (format-id #'id "remove-~a" #'id)]
[id? (format-id #'id "~a?" #'id)]
[id* (format-id #'id "~a*" #'id)]
@ -80,7 +98,7 @@
(if (pair? sis-in)
(apply append sis-in)
(list
(let ([si (make-syntax-introducer)])
(let ([si (make-syntax-introducer #t)])
(list (procedure-rename (curryr si 'add) 'add-id)
(procedure-rename (curryr si 'flip) 'flip-id)
(procedure-rename (curryr si 'remove) 'remove-id)))))))
@ -88,13 +106,19 @@
(define flip-id (λ(x) ((apply compose1 (map cadr id-sis)) (->syntax x))))
(define remove-id (λ(x) ((apply compose1 (map caddr id-sis)) (->syntax x))))
(define (id x) (add-id (datum->syntax #f (syntax-e (->syntax x)))))
(define (id-binding-form x) (syntax-local-introduce (id x)))
(define (id* x) (replace-context (add-id (datum->syntax #f '_)) (->syntax x)))
(define (id? x)
(and
(member (car (context (add-id (datum->syntax #f '_))))
(context (->syntax x)))
#t))))]))
#t))
(define-syntax-rule (with-id-syntax ([pat val] (... ...)) . body)
(with-syntax ([pat (id* val)] (... ...)) . body))
(define-syntax-rule (with-id-binding-form ([pat val] (... ...)) . body)
(with-syntax ([pat (id-binding-form val)] (... ...)) . body))
(define-syntax-rule (let-id-syntax ([pat val] (... ...)) . body)
(let-syntax ([pat (id* val)] (... ...)) . body))))]))
(define (scopes-equal? stxl stxr)
;; "A bound-identifier=? comparison checks that two identifiers have exactly the same scope sets"
@ -102,44 +126,44 @@
(module+ test
(require rackunit)
(define-scope red)
(define stx (datum->syntax #f 'x))
(define red-stx (add-red stx))
(define double-red-stx (add-red (add-red stx)))
(check-false (red? stx))
(check-true (red? red-stx))
(check-true (red? double-red-stx))
(check-false (scopes-equal? stx red-stx))
(check-true (scopes-equal? red-stx double-red-stx))
(check-false (scopes-equal? red-stx (remove-red double-red-stx)))
(define-scope blue) ; scope addition is commutative
(define blue-stx (blue stx))
(check-true (scopes-equal? (add-blue red-stx) (add-red blue-stx)))
(check-true (scopes-equal? (remove-red (add-blue red-stx)) (remove-red (add-red blue-stx))))
(define-scope green) ; replace scopes at outer layer
(check-true (scopes-equal? (green red-stx) (green blue-stx)))
;; replace scopes everywhere
(check-true (scopes-equal? (car (syntax->list (green* #`(#,blue-stx #,red-stx))))
(car (syntax->list (green* #`(#,red-stx #,blue-stx))))))
;; todo: test flipping
(define-scope purple (red blue))
(check-true (purple? (add-purple stx)))
(check-true (scopes-equal? (purple (green stx)) (add-blue (remove-green (add-red (add-green (add-blue stx))))))))
(require rackunit)
(define-scope red)
(define stx (datum->syntax #f 'x))
(define red-stx (add-red stx))
(define double-red-stx (add-red (add-red stx)))
(check-false (red? stx))
(check-true (red? red-stx))
(check-true (red? double-red-stx))
(check-false (scopes-equal? stx red-stx))
(check-true (scopes-equal? red-stx double-red-stx))
(check-false (scopes-equal? red-stx (remove-red double-red-stx)))
(define-scope blue) ; scope addition is commutative
(define blue-stx (blue stx))
(check-true (scopes-equal? (add-blue red-stx) (add-red blue-stx)))
(check-true (scopes-equal? (remove-red (add-blue red-stx)) (remove-red (add-red blue-stx))))
(define-scope green) ; replace scopes at outer layer
(check-true (scopes-equal? (green red-stx) (green blue-stx)))
;; replace scopes everywhere
(check-true (scopes-equal? (car (syntax->list (green* #`(#,blue-stx #,red-stx))))
(car (syntax->list (green* #`(#,red-stx #,blue-stx))))))
;; todo: test flipping
(define-scope purple (red blue))
(check-true (purple? (add-purple stx)))
(check-true (scopes-equal? (purple (green stx)) (add-blue (remove-green (add-red (add-green (add-blue stx))))))))
(define-syntax (with-scopes stx)