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18 lines
601 B
Racket
18 lines
601 B
Racket
3 years ago
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#lang racket/base
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(require racket/contract)
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(provide (all-defined-out))
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(define pass/c (any/c . -> . any/c))
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(define-syntax-rule (define-pass (PASS-NAME ARG)
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#:precondition PRECOND-PROC
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#:postcondition POSTCOND-PROC
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EXPRS ...)
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(define/contract (PASS-NAME ARG)
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pass/c
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(unless (PRECOND-PROC ARG)
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(error 'PASS-NAME (format "precondition failed: ~a" 'PRECOND-PROC)))
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(define res (let () EXPRS ...))
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(unless (POSTCOND-PROC res)
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(error 'PASS-NAME (format "postcondition failed: ~a" 'POSTCOND-PROC)))
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res))
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