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tweaks

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This commit is contained in:
Matthew Butterick 2016-04-29 16:05:58 -07:00
parent a7112554e3
commit fb0522957a
1 changed files with 25 additions and 26 deletions
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51
beautiful-racket-lib/br/define.rkt
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@ -1,5 +1,5 @@
#lang racket/base
(require (for-syntax racket/list racket/base syntax/parse racket/syntax syntax/datum syntax/strip-context) sugar/define)
(require (for-syntax racket/list racket/base syntax/parse racket/syntax syntax/datum syntax/strip-context racket/string) sugar/define)
(provide (all-defined-out))
;; everything is prefixed br: whether it needs it or not so it can be stripped by #lang br
@ -14,13 +14,13 @@
(define-for-syntax (generate-literals pats)
;; generate literals for any symbols that are not ... or _ or _underscore-prefixed
(for*/list ([pat-arg (in-list (syntax-flatten pats))]
[pat-datum (in-value (syntax->datum pat-arg))]
#:when (and (symbol? pat-datum)
(not (eq? pat-datum '...)) (not (eq? pat-datum '_)) (not (eq? pat-datum 'else))
(not (let ([str (symbol->string pat-datum)])
(regexp-match #rx"^_" str)))))
pat-arg))
(define pattern-arg-prefixer "_")
(for/list ([pat-arg (in-list (syntax-flatten pats))]
#:when (let ([pat-datum (syntax->datum pat-arg)])
(and (symbol? pat-datum)
(not (member pat-datum '(... _ else))) ; exempted from literality
(not (string-prefix? (symbol->string pat-datum) pattern-arg-prefixer)))))
pat-arg))
;; expose the caller context within br:define macros with syntax parameter
(begin-for-syntax
@ -65,28 +65,26 @@
#'((pat result-expr) ... else-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)))])]
[(LITERAL ...) (generate-literals #'(pat ...))])
[LITERALS (generate-literals #'(pat ...))])
#'(define-syntax top-id.name (λ (stx)
(define result
(syntax-case stx (LITERAL ...)
(syntax-case stx LITERALS
[pat (syntax-parameterize ([caller-stx (make-rename-transformer #'stx)])
(syntax-parameterize ([shared-syntax (make-shared-syntax-macro caller-stx)])
result-expr))] ...
[else else-result-expr]))
(if (not (syntax? result))
(datum->syntax #'top-id.name result)
result))))]
(if (syntax? result)
result
(datum->syntax #'top-id.name result)))))]
;; function matcher
[(_ top-id:id [(_ pat-arg ... . rest-arg) body ...] ...)
[(_ top-id:id [(_ . pat-args) . body] ...)
#'(define top-id
(case-lambda
[(pat-arg ... . rest-arg) body ...] ...
[pat-args . body] ...
[else (raise-syntax-error 'define-cases "no matching case for argument pattern" (object-name top-id))]))]))
(module+ test
(require rackunit)
(define foo-val 'got-foo-val)
@ -147,8 +145,8 @@
#:literals (syntax)
;; syntax
[(_ (syntax (id pat-arg ... . rest-arg)) body ...) ; (define #'(foo arg) #'(+ arg arg))
#'(br:define-cases (syntax id) [(syntax (_ pat-arg ... . rest-arg)) body ...])]
[(_ (syntax (id . pat-args)) . body) ; (define #'(foo arg) #'(+ arg arg))
#'(br:define-cases (syntax id) [(syntax (_ . pat-args)) . body])]
[(_ sid:syntaxed-id sid2:syntaxed-id) ; (define #'f1 #'f2)
#'(define-syntax sid.name (make-rename-transformer sid2))]
@ -162,9 +160,10 @@
[(_ sid:syntaxed-id (λ (stx-arg ...) expr ...)) ; (define #'f1 (λ(stx) expr ...)
#:fail-when (not (= (length (syntax->datum #'(stx-arg ...))) 1))
(raise-syntax-error 'define "did not get exactly one argument for macro" (syntax->datum #'(stx-arg ...)))
#'(define-syntax (sid.name stx-arg ...) expr ...)]
(with-syntax ([(first-stx-arg other ...) #'(stx-arg ...)])
#'(define-syntax (sid.name first-stx-arg) expr ...))]
[(_ args ...) #'(define args ...)]))
[(_ arg ...) #'(define arg ...)]))
(module+ test
(require rackunit)
@ -254,7 +253,7 @@
(define-syntax (br:define-cases-inverting stx)
(syntax-case stx (syntax)
[(_ (syntax _id) [(syntax _pat) . _bodyexprs] ...)
(with-syntax ([(LITERAL ...) (generate-literals #'(_pat ...))])
(with-syntax ([LITERALS (generate-literals #'(_pat ...))])
#'(define-syntax (_id stx)
(syntax-case stx ()
[(_id . rest)
@ -262,14 +261,14 @@
[fused-stx (with-syntax ([(expanded-macro (... ...)) expanded-macros])
#`(_id expanded-macro (... ...)))])
(define result
(syntax-case fused-stx (LITERAL ...) ;; put id back together with args to make whole pattern
(syntax-case fused-stx LITERALS ;; put id back together with args to make whole pattern
[_pat (syntax-parameterize ([caller-stx (make-rename-transformer #'stx)])
(syntax-parameterize ([shared-syntax (make-shared-syntax-macro caller-stx)])
. _bodyexprs))] ...
[else (raise-syntax-error 'define-cases-inverting (format "no matching case for syntax pattern ~v" (syntax->datum stx)) (syntax->datum #'_id))]))
(if (not (syntax? result))
(datum->syntax #'_id result)
result))])))]))
(if (syntax? result)
result
(datum->syntax #'_id result)))])))]))
(module+ test