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24 lines
756 B
Racket
24 lines
756 B
Racket
#lang racket/base
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(require (for-syntax racket/base) br/define)
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(provide (all-defined-out))
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(define-macro (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
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[(match-vals) . result] (... ...)
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[else . else-result])
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#'(cond
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[(PRED test-val '(match-vals)) . result] (... ...)
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[else . else-result])]
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[(_ test-val
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match-clause (... ...))
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#'(ID test-val
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match-clause (... ...)
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[else (error 'ID "no match")])])))
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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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;; `eqv?` is OK for chars (same as `char=?`)
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(define-case-macro casev memv) |