92d1dd1c5e
This enables contract generation in the negative direction (untyped->typed) for row polymorphic types (basically mixin types). Depends on `class-seal` and `class-unseal` in the racket/class library.
36 lines
844 B
Racket
36 lines
844 B
Racket
#;
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(exn-pred #rx"unrelated class")
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#lang racket/base
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(module u racket
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(define state #f)
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;; don't allow smuggling with mutation either
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(define (mixin cls)
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(define result
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(if (not state)
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(class cls
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(super-new)
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(define/public (n x) x))
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;; should subclass from cls, not state since otherwise
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;; we lose the `m` method
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(class state (super-new))))
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(set! state cls)
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result)
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(provide mixin))
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(module t typed/racket
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(require/typed (submod ".." u)
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[mixin
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(All (r #:row)
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(-> (Class #:row-var r)
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(Class #:row-var r [n (-> Integer Integer)])))])
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(mixin (class object% (super-new)))
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(mixin (class object%
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(super-new)
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(define/public (m x) x))))
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(require 't)
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