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26 lines
993 B
Racket
26 lines
993 B
Racket
#lang racket/base
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(require (for-syntax racket/base racket/syntax))
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(provide (all-defined-out))
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(define-syntax-rule (define-case-macro ID PRED)
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(define-syntax (ID stx)
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(syntax-case stx ()
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[(_ TEST-VAL [(MATCH0 . MATCH-VALS) . RESULT] (... ...) [else . ELSE-RESULT])
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#'(cond
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[(PRED TEST-VAL '(MATCH0 . MATCH-VALS)) . RESULT] (... ...)
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[else . ELSE-RESULT])]
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[(_ TEST-VAL MATCH-CLAUSE (... ...))
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#'(ID TEST-VAL
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MATCH-CLAUSE (... ...)
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[else (error 'ID (format "no match for ~a" TEST-VAL))])])))
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;; like case but strictly uses `eq?` comparison (as opposed to `equal?`)
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(define-case-macro caseq memq)
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(define-case-macro casev memv)
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(require sugar/debug)
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(define-syntax (cond-report stx)
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(syntax-case stx ()
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[(_ [COND . BODY] ... [else . ELSE-BODY]) #'(cond [(report COND) (report (let () (void) . BODY))] ... [else . ELSE-BODY])]
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[(_ [COND . BODY] ... ) #'(cond-report [COND . BODY] ... [else (void)])])) |