b4a4c174e4
Adds intersection types as a better way to handle the the case when restrict cannot structurally intersect two types (e.g. when you learn within a polymorphic function a variable x of type A is also an Integer, but we dont know how A relates to Integer). This allows for non-lossy refinements of type info while typechecking.
20 lines
284 B
Racket
20 lines
284 B
Racket
#lang racket/base
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(module a typed/racket
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(provide num-id)
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(: num-id (∀ (A) (-> (∩ Number A) (∩ Number A))))
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(define (num-id x) x))
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(require 'a)
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(let ()
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(num-id 42)
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(void))
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(with-handlers ([exn:fail:contract?
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(λ (ex) (void))])
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(num-id "42"))
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