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246 lines
8.4 KiB
Racket
246 lines
8.4 KiB
Racket
#lang racket/base
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(require racket/function
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(for-syntax racket/base
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syntax/parse
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br/private/generate-literals
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syntax/define))
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(provide (all-defined-out)
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(for-syntax with-shared-id))
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(module+ test (require rackunit))
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(begin-for-syntax
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;; expose the caller context within br:define macros with syntax parameter
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(require (for-syntax racket/base) racket/stxparam)
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(provide caller-stx)
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(define-syntax-parameter caller-stx (λ(stx) (error 'caller-stx-not-parameterized))))
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(define-syntax (define-cases stx)
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(syntax-parse stx
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#:literals (syntax)
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[(_ id:id)
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(raise-syntax-error 'define-cases "no cases given" (syntax->datum #'id))]
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[(_ id:id [(_ . pat-args:expr) . body:expr] ...)
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#'(define id
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(case-lambda
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[pat-args . body] ...
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[rest-pat (apply raise-arity-error 'id (normalize-arity (map length '(pat-args ...))) rest-pat)]))]
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[else (raise-syntax-error
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'define-cases
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"no matching case for calling pattern"
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(syntax->datum stx))]))
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(module+ test
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(define-cases f
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[(_ arg) (add1 arg)]
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[(_ arg1 arg2) (+ arg1 arg2)]
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[(_ . any) 'boing])
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(check-equal? (f 42) 43)
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(check-equal? (f 42 5) 47)
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(check-equal? (f 42 5 'zonk) 'boing)
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(define-cases f-one-arg
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[(_ arg) (add1 arg)])
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(check-exn exn:fail:contract:arity? (λ _ (f-one-arg 1 2 3))))
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(define-syntax-rule (debug-define-macro (ID . PAT-ARGS) BODY)
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(define-macro (ID . PAT-ARGS)
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#`(begin
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(for-each displayln
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(list
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(format "input pattern = #'~a" '#,'(ID . PAT-ARGS))
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(format "output pattern = #'~a" (cadr '#,'BODY))
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(format "invoked as = ~a" (syntax->datum #'(ID . PAT-ARGS)))
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(format "expanded as = ~a" '#,(syntax->datum BODY))
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(format "evaluated as = ~a" #,BODY)))
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#,BODY)))
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(module+ test
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(require racket/port)
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(parameterize ([current-output-port (open-output-nowhere)])
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(check-equal? (let ()
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(debug-define-macro (foo X Y Z)
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#'(apply + (list X Y Z)))
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(foo 1 2 3)) 6)
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(check-equal? (let ()
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(debug-define-macro (foo X ...) #'(apply * (list X ...)))
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(foo 10 11 12)) 1320)))
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(begin-for-syntax
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(begin-for-syntax
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(require (for-syntax racket/base))
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(define-syntax-rule (make-shared-syntax-macro caller-stx)
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#'(syntax-rules stx
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[(_ form)
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#'(datum->syntax caller-stx (if (syntax? form)
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(syntax-e form)
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form))]))))
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(module+ test
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(define-macro (dirty-maker ARG)
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(with-syntax ([dirty-bar (datum->syntax caller-stx 'dirty-bar)])
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#'(define dirty-bar (* ARG 2))))
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(dirty-maker 42)
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(check-equal? dirty-bar 84))
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(begin-for-syntax
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(define-syntax-rule (with-shared-id (id ...) . body)
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(with-syntax ([id (datum->syntax caller-stx 'id)] ...)
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. body)))
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;; `syntax-parse` classes shared by `define-macro` and `define-macro-cases`
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(begin-for-syntax
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(require syntax/parse)
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(define-syntax-class syntaxed-id
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#:literals (syntax quasisyntax)
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#:description "id in syntaxed form"
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(pattern ([~or syntax quasisyntax] name:id)))
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(define-syntax-class syntaxed-thing
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#:literals (syntax quasisyntax)
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#:description "some datum in syntaxed form"
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(pattern ([~or syntax quasisyntax] thing:expr)))
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(define-syntax-class else-clause
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#:literals (else)
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(pattern [else . body:expr]))
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(define-syntax-class transformer-func
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#:literals (lambda λ)
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(pattern ([~or lambda λ] (arg:id) . body:expr))))
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(define-syntax (define-macro stx)
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(syntax-parse stx
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[(_ id:id stxed-id:syntaxed-id)
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#'(define-syntax id (make-rename-transformer stxed-id))]
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[(_ id:id func:transformer-func)
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#'(define-syntax id func)]
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[(_ id:id func-id:id)
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#'(define-syntax id func-id)]
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[(_ id:id stxed-thing:syntaxed-thing)
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#'(define-macro id (λ (stx) stxed-thing))]
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[(_ (id:id . patargs:expr) . body:expr)
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(with-syntax ([id (syntax-property #'id 'caller 'define-macro)])
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#'(define-macro-cases id [(id . patargs) (begin . body)]))]
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[else (raise-syntax-error
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'define-macro
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"no matching case for calling pattern"
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(syntax->datum stx))]))
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(define-syntax (define-macro-cases stx)
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(define (error-source stx) (or (syntax-property stx 'caller) 'define-macro-cases))
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(syntax-parse stx
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[(_ id:id)
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(raise-syntax-error (error-source #'id) "no cases given" (syntax->datum #'id))]
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[(_ id:id leading-pat:expr ... else-pat:else-clause trailing-pat0:expr trailing-pat:expr ...)
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(raise-syntax-error (error-source #'id) "`else` clause must be last" (syntax->datum #'id))]
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[(_ id:id (pat:expr . result-exprs:expr) ... else-clause:else-clause)
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(unless (ellipses-follow-wildcards-or-subpatterns? #'(pat ...))
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(raise-syntax-error (error-source #'id) "ellipsis in pattern can only appear after wildcard or subpattern" (syntax->datum stx)))
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(with-syntax ([(PAT ...) (map (λ (x) (literalize-pat x #'~literal)) (syntax->list #'(pat ...)))])
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#'(define-macro id
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(λ (stx)
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(define result
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(syntax-parameterize ([caller-stx (make-rename-transformer #'stx)])
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(syntax-parse (syntax-case stx () [any #'any])
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[PAT . result-exprs] ...
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else-clause)))
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(if (syntax? result)
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result
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(datum->syntax #'id result)))))]
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[(_ id:id pat-clause:expr ...) ; macro without `else` clause will reach this branch
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#'(define-macro-cases id
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pat-clause ...
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[else (raise-syntax-error
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'id
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"no matching case for calling pattern"
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(syntax->datum caller-stx))])]
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[else (raise-syntax-error
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(error-source #'id)
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"no matching case for calling pattern"
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(syntax->datum stx))]))
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(module+ test
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(define-macro plus (λ (stx) #'+))
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(check-equal? (plus 42) +)
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(define-macro plusser #'plus)
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(check-equal? (plusser 42) +)
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(check-equal? plusser +)
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(define-macro (times [nested ARG]) #`(* ARG ARG))
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(check-equal? (times [nested 10]) 100)
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(define-macro timeser #'times)
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(check-equal? (timeser [nested 12]) 144)
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(define-macro fortytwo #`42)
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(check-equal? fortytwo 42)
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(check-equal? (let ()
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(define-macro (foo X)
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(with-syntax ([zam #'+])
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#'(zam X X))) (foo 42)) 84)
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(begin
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(define-macro (redefine ID) #'(define ID 42))
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(redefine zoombar)
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(check-equal? zoombar 42))
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;; use caller-stx parameter to introduce identifier unhygienically
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(define-macro (zam ARG1 ARG2 ARG3)
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(with-syntax ([dz (datum->syntax caller-stx 'dirty-zam)])
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#`(define dz 'got-dirty-zam)))
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(zam 'this 'that 42)
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(check-equal? dirty-zam 'got-dirty-zam)
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(define-macro (add X) #'(+ X X))
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(check-equal? (add 5) 10)
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(define-macro (add-b 9X) #'(+ 9X 9X))
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(check-equal? (add-b 5) 10)
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(define-macro-cases add-again [(_ X) #'(+ X X)])
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(check-equal? (add-again 5) 10)
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(define-macro-cases add-3rd [(_ X) #'(+ X X)])
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(check-equal? (add-3rd 5) 10)
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(define-macro add-4th #'add-3rd)
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(check-equal? (add-4th 5) 10)
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(define foo-val 'got-foo-val)
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(define (foo-func) 'got-foo-func)
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(define-macro-cases op
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[(_ "+") #''got-plus]
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[(_ ARG) #''got-something-else]
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[(_) #'(foo-func)]
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[_ #'foo-val])
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(check-equal? (op "+") 'got-plus)
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(check-equal? (op 42) 'got-something-else)
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(check-equal? (op) 'got-foo-func)
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(check-equal? op 'got-foo-val)
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(define-macro-cases elseop
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[(_ ARG) #''got-arg]
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[else #''got-else])
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(check-equal? (elseop "+") 'got-arg)
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(check-equal? (elseop "+" 42) 'got-else)
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(check-exn exn:fail:syntax? (λ () (expand-once #'(define-macro-cases no-cases))))
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(check-exn exn:fail:syntax? (λ () (expand-once #'(define-macro-cases badelseop
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[else #''got-else]
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[(_ _arg) #''got-arg]))))
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(define-macro-cases no-else-macro
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[(_ ARG) #''got-arg])
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(check-exn exn:fail:syntax? (λ _ (expand-once #'(no-else-macro 'arg1 'arg2)))))
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(define-macro (define-unhygienic-macro (ID PAT ...) BODY ... STX-OBJECT)
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#'(define-macro (ID PAT ...)
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BODY ...
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(datum->syntax caller-stx (syntax->datum STX-OBJECT))))
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