macrotypes/typed-lang-builder/examples/fomega3.rkt
2016-06-28 13:22:58 -04:00

34 lines
1.4 KiB
Racket

#lang typed-lang-builder
(extends "sysf.rkt" #:except #%datum Λ inst)
(reuse String #%datum #:from "stlc+reco+var.rkt")
(require (only-in "fomega.rkt" current-kind? ∀★? ★? kind?))
(reuse Λ inst define-type-alias ∀★ #:from "fomega.rkt")
; same as fomega2.rkt --- λ and #%app works as both regular and type versions,
; → is both type and kind --- but reuses parts of fomega.rkt,
; ie removes the duplication in fomega2.rkt
;; System F_omega
;; Type relation:
;; - redefine current-kind? and current-type so #%app and λ
;; work for both terms and types
;; Types:
;; - types from fomega.rkt
;; - String from stlc+reco+var
;; Terms:
;; - extend ∀ Λ inst from fomega.rkt
;; - #%datum from stlc+reco+var
;; types and kinds are now mixed, due to #%app and λ
(begin-for-syntax
(current-kind? (λ (k) (or (#%type? k) (kind? k) (#%type? (typeof k)))))
;; Try to keep "type?" backward compatible with its uses so far,
;; eg in the definition of λ or previous type constuctors.
;; (However, this is not completely possible, eg define-type-alias)
;; So now "type?" no longer validates types, rather it's a subset.
;; But we no longer need type? to validate types, instead we can use (kind? (typeof t))
(current-type? (λ (t) (or (type? t)
(let ([k (typeof t)])
(or (★? k) (∀★? k)))
((current-kind?) t)))))