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This commit is contained in:
Matthew Butterick 2016-04-29 19:59:53 -07:00
parent 5a0e8982b7
commit 56777d4ca3
1 changed files with 23 additions and 25 deletions
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48
beautiful-racket-lib/br/define.rkt
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@ -49,7 +49,7 @@
(raise-syntax-error 'define-cases "no cases given" (syntax->datum #'top-id))] (raise-syntax-error 'define-cases "no cases given" (syntax->datum #'top-id))]
;; defective for syntax ;; defective for syntax
[(_ (sid:syntaxed-id _ ...) _ ...) ; (define (#'f1 stx) expr ...) [(_ (sid:syntaxed-id . _) . _) ; (define (#'f1 stx) expr ...)
(raise-syntax-error 'define-cases "definition of a syntax transformer must use lambda notation, because otherwise it's too easy to confuse the compile-time shape and the run-time shape" (syntax->datum #'sid.name))] (raise-syntax-error 'define-cases "definition of a syntax transformer must use lambda notation, because otherwise it's too easy to confuse the compile-time shape and the run-time shape" (syntax->datum #'sid.name))]
;; syntax matcher ;; syntax matcher
@ -59,20 +59,20 @@
[((pat result) ... last-one) #'(pat ...)])))]) [((pat result) ... last-one) #'(pat ...)])))])
(when (member 'else all-but-last-pat-datums) (when (member 'else all-but-last-pat-datums)
(raise-syntax-error 'define-cases "else case must be last" (syntax->datum #'top-id.name)))) (raise-syntax-error 'define-cases "else case must be last" (syntax->datum #'top-id.name))))
(with-syntax* ([((pat result-expr) ... else-result-expr) (with-syntax* ([((pat . result-exprs) ... else-result-exprs)
(syntax-case #'patexprs (syntax else) (syntax-case #'patexprs (syntax else)
[(((syntax pat) result-expr) ... (else else-result-expr)) [(((syntax pat) result-expr) ... (else . else-result-exprs))
#'((pat result-expr) ... else-result-expr)] #'((pat result-expr) ... else-result-exprs)]
[(((syntax pat) result-expr) ...) [(((syntax pat) result-expr) ...)
#'((pat result-expr) ... (raise-syntax-error 'define-cases (format "no matching case for syntax pattern ~v" (syntax->datum stx)) (syntax->datum #'top-id.name)))])] #'((pat result-expr) ... (list (raise-syntax-error 'define-cases (format "no matching case for syntax pattern ~v" (syntax->datum stx)) (syntax->datum #'top-id.name))))])]
[LITERALS (generate-literals #'(pat ...))]) [LITERALS (generate-literals #'(pat ...))])
#'(define-syntax top-id.name (λ (stx) #'(define-syntax top-id.name (λ (stx)
(define result (define result
(syntax-case stx LITERALS (syntax-case stx LITERALS
[pat (syntax-parameterize ([caller-stx (make-rename-transformer #'stx)]) [pat (syntax-parameterize ([caller-stx (make-rename-transformer #'stx)])
(syntax-parameterize ([shared-syntax (make-shared-syntax-macro caller-stx)]) (syntax-parameterize ([shared-syntax (make-shared-syntax-macro caller-stx)])
result-expr))] ... . result-exprs))] ...
[else else-result-expr])) [else . else-result-exprs]))
(if (syntax? result) (if (syntax? result)
result result
(datum->syntax #'top-id.name result)))))] (datum->syntax #'top-id.name result)))))]
@ -118,12 +118,11 @@
[(_ arg1 arg2) (+ arg1 arg2)]) [(_ arg1 arg2) (+ arg1 arg2)])
(check-equal? (f 42) 43) (check-equal? (f 42) 43)
(check-equal? (f 42 5) 47) (check-equal? (f 42 5) 47))
;; todo: error from define-cases not trapped by check-exn ;; todo: error from define-cases not trapped by check-exn
;;(check-exn exn:fail:syntax? (λ _ (define-cases (#'times stx stx2) #'*))) ;;(check-exn exn:fail:syntax? (λ _ (define-cases (#'times stx stx2) #'*)))
)
@ -198,14 +197,14 @@
(check-equal? dirty-zam 'got-dirty-zam)) (check-equal? dirty-zam 'got-dirty-zam))
(define-syntax-rule (br:debug-define (syntax (id pat-arg ... . rest-arg)) body-exp) (define-syntax-rule (br:debug-define (syntax (id . pat-args)) body-exp)
(br:define #'(id pat-arg ... . rest-arg) (br:define #'(id . pat-args)
#`(begin #`(begin
(for-each displayln (for-each displayln
(list (list
(format "input pattern = #'~a" '#,'(id pat-arg ... . rest-arg)) (format "input pattern = #'~a" '#,'(id . pat-args))
(format "output pattern = #'~a" (cadr '#,'body-exp)) (format "output pattern = #'~a" (cadr '#,'body-exp))
(format "invoked as = ~a" (syntax->datum #'(id pat-arg ... . rest-arg))) (format "invoked as = ~a" (syntax->datum #'(id . pat-args)))
(format "expanded as = ~a" '#,(syntax->datum body-exp)) (format "expanded as = ~a" '#,(syntax->datum body-exp))
(format "evaluated as = ~a" #,body-exp))) (format "evaluated as = ~a" #,body-exp)))
#,body-exp))) #,body-exp)))
@ -224,8 +223,8 @@
(define-syntax-rule (br:define+provide arg ...) (define-syntax-rule (br:define+provide . args)
(define+provide arg ...)) (define+provide . args))
(define-for-syntax (expand-macro mac) (define-for-syntax (expand-macro mac)
@ -234,9 +233,9 @@
(define-syntax (br:define-inverting stx) (define-syntax (br:define-inverting stx)
(syntax-case stx (syntax) (syntax-case stx (syntax)
[(_ (syntax (_id _patarg ... . _restarg)) _syntaxexpr ...) [(_ (syntax (_id . _pat-args)) . _syntaxexprs)
#'(br:define-cases-inverting (syntax _id) #'(br:define-cases-inverting (syntax _id)
[(syntax (_ _patarg ... . _restarg)) _syntaxexpr ...])])) [(syntax (_ . _pat-args)) . _syntaxexprs])]))
(begin-for-syntax (begin-for-syntax
(begin-for-syntax (begin-for-syntax
@ -252,17 +251,16 @@
(define-syntax (br:define-cases-inverting stx) (define-syntax (br:define-cases-inverting stx)
(syntax-case stx (syntax) (syntax-case stx (syntax)
[(_ (syntax _id) [(syntax _pat) . _bodyexprs] ...) [(_ (syntax _id) [(syntax _patarg) . _bodyexprs] ...)
(with-syntax ([LITERALS (generate-literals #'(_pat ...))]) (with-syntax ([LITERALS (generate-literals #'(_patarg ...))])
#'(define-syntax (_id stx) #'(define-syntax (_id stx)
(syntax-case stx () (syntax-case stx ()
[(_id . rest) [(_id . rest)
(let* ([expanded-macros (map expand-macro (syntax->list #'rest))] (let* ([expanded-stx (with-syntax ([expanded-macros (map expand-macro (syntax->list #'rest))])
[fused-stx (with-syntax ([(expanded-macro (... ...)) expanded-macros]) #'(_id . expanded-macros))])
#`(_id expanded-macro (... ...)))])
(define result (define result
(syntax-case fused-stx LITERALS ;; put id back together with args to make whole pattern (syntax-case expanded-stx LITERALS
[_pat (syntax-parameterize ([caller-stx (make-rename-transformer #'stx)]) [_patarg (syntax-parameterize ([caller-stx (make-rename-transformer #'stx)])
(syntax-parameterize ([shared-syntax (make-shared-syntax-macro caller-stx)]) (syntax-parameterize ([shared-syntax (make-shared-syntax-macro caller-stx)])
. _bodyexprs))] ... . _bodyexprs))] ...
[else (raise-syntax-error 'define-cases-inverting (format "no matching case for syntax pattern ~v" (syntax->datum stx)) (syntax->datum #'_id))])) [else (raise-syntax-error 'define-cases-inverting (format "no matching case for syntax pattern ~v" (syntax->datum stx)) (syntax->datum #'_id))]))