bf126449b4
- use this to impl forall in fomega - define-type-constructor default arity is =1 - define explicit normalize fn in fomega -- speeds up tests 15% - move same-type to define-syntax-category
36 lines
955 B
Racket
36 lines
955 B
Racket
#lang s-exp "typecheck.rkt"
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(extends "stlc+reco+var.rkt")
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;; Simply-Typed Lambda Calculus, plus cons
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;; Types:
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;; - types from stlc+reco+var.rkt
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;; - List constructor
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;; Terms:
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;; - terms from stlc+reco+var.rkt
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;; TODO: enable HO use of list primitives
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(define-type-constructor List)
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(define-typed-syntax nil
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[(_ ~! τi:type-ann) (⊢ null : (List τi.norm))]
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[_:id #:fail-when #t (error 'nil "requires type annotation") #'(void)])
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(define-typed-syntax cons
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[(_ e1 e2)
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#:with (e1- τ1) (infer+erase #'e1)
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#:with (e2- (τ2)) (⇑ e2 as List)
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#:when (typecheck? #'τ1 #'τ2)
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(⊢ (cons e1- e2-) : (List τ1))])
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(define-typed-syntax isnil
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[(_ e)
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#:with (e- _) (⇑ e as List)
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(⊢ (null? e-) : Bool)])
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(define-typed-syntax head
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[(_ e)
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#:with (e- (τ)) (⇑ e as List)
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(⊢ (car e-) : τ)])
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(define-typed-syntax tail
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[(_ e)
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#:with (e- τ-lst) (infer+erase #'e)
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#:when (List? #'τ-lst)
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(⊢ (cdr e-) : τ-lst)]) |