19 lines
719 B
Racket
19 lines
719 B
Racket
#lang typed/racket/base
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;; Limited support for reasoning about subtyped of a polymorphic base struct type in TR.
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(require (for-syntax racket/base))
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(require racket/match)
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(provide pseudo-substruct:)
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(define-syntax-rule (pseudo-substruct: (super-type TypeParam ...) SubType sub-type sub-type?)
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(begin (define-type SubType (super-type TypeParam ...))
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(define-predicate sub-type? SubType)
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(define-match-expander sub-type
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(lambda (stx)
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(syntax-case stx () [(_ f (... ...)) #'(? sub-type? (super-type f (... ...)))]))
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(lambda (stx)
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(syntax-case stx ()
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[x (identifier? #'x) #'(inst super-type TypeParam ...)]
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[(_ f (... ...)) #'((inst super-type TypeParam ...) f (... ...))])))))
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