23 lines
588 B
Racket
23 lines
588 B
Racket
#lang s-exp "../redex-curnel.rkt"
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(provide bool btrue bfalse if bnot)
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(data bool : Type
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(btrue : bool)
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(bfalse : bool))
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(define-syntax (if syn)
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(syntax-case syn ()
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[(_ t s f)
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;; Compute the motive
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(let* ([sty (type-infer/syn #'s)]
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[M #`(lambda (x : #,(type-infer/syn #'t))
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#,sty)]
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[U (type-infer/syn sty)])
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(quasisyntax/loc syn (elim bool #,U #,M s f t)))]))
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(define (bnot (x : bool)) (if x bfalse btrue))
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(module+ test
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(require rackunit)
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(check-equal? (bnot btrue) bfalse)
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(check-equal? (bnot bfalse) btrue))
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