1537 lines
57 KiB
Racket
1537 lines
57 KiB
Racket
#lang turnstile
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(provide (all-defined-out)
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(for-syntax (all-defined-out))
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(for-meta 2 (all-defined-out)))
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(require (only-in turnstile
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[define-type-constructor define-type-constructor-]))
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(require (prefix-in syndicate: syndicate/actor-lang))
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(require (for-meta 2 macrotypes/stx-utils racket/list syntax/stx syntax/parse racket/base))
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(require (for-syntax turnstile/examples/util/filter-maximal))
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(require (for-syntax macrotypes/type-constraints macrotypes/variance-constraints))
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#;(require (only-in (for-syntax macrotypes/typecheck-core) get-orig))
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(require (for-syntax racket/struct-info
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syntax/id-table))
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(require macrotypes/postfix-in)
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(require (rename-in racket/math [exact-truncate exact-truncate-]))
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(require (postfix-in - racket/list))
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(require (postfix-in - racket/set))
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(require (postfix-in - racket/match))
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(require (postfix-in - (only-in racket/format ~a)))
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(module+ test
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(require rackunit)
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(require rackunit/turnstile))
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;; Type Checking Conventions
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;; : describes the immediate result of evaluation
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;; ν-ep key aggregates endpoint affects:
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;; `Shares`, `Reacts`, and `MakesField`
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;; Note thar MakesField is only an effect, not a type
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;; ν-f key aggregates facet effects (starting/stopping a facet) as `Role`s & `Stop`s and message sends, `Sends`
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;; ν-s key aggregates spawned actors as `Actor`s
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;; Types
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;; certain metadata needs to be associated with each type, for the purpose of
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;; making certain judgments and metafunctions extensible.
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(begin-for-syntax
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(struct type-metadata (isec cons) #:transparent)
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;; (MutableHashOf Symbol type-metadata)
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(define TypeInfo# (make-hash))
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;; Identifier isect-desc TypeCons -> Void
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(define (set-type-info! ty-cons isec cons)
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(when (hash-has-key? TypeInfo# ty-cons)
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;; TODO
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#f)
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(hash-set! TypeInfo#
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ty-cons
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(type-metadata isec cons)))
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;; Identifier -> Symbol
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;; XYZ-.*
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;; based on the convention used by turnstile *shrug*
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(define (un- id)
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(define match?
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(regexp-match #px"^(\\S*)-\\S*$" (symbol->string (syntax-e id))))
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(string->symbol (second match?)))
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;; Identifier -> (U #f type-metadata)
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(define (get-type-info ty-cons)
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(hash-ref TypeInfo# (un- ty-cons) #f))
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;; Identifier -> (U #f isec-desc)
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(define (get-type-isec-desc ty-cons)
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(define result? (get-type-info ty-cons))
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(and result? (type-metadata-isec result?)))
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;; Identifier -> (U #f TypeCons)
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(define (get-type-cons ty-cons)
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(define result? (get-type-info ty-cons))
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(and result? (type-metadata-cons result?)))
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;; a isect-desc describes how a type (constructor) behaves with respect to
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;; intersection, and is one of
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;; - BASE
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;; - CONTAINER-LIKE
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;; - PRODUCT-LIKE
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(define BASE 'base)
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(define CONTAINER-LIKE 'container-like)
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(define PRODUCT-LIKE 'product-like)
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;; syntax property key
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#;(define isect-desc-key
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'isect-desc-key)
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(define-syntax-class isect-desc
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#:attributes (val)
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#:datum-literals (BASE CONTAINER-LIKE PRODUCT-LIKE)
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(pattern BASE
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#:attr val BASE)
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(pattern CONTAINER-LIKE
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#:attr val CONTAINER-LIKE)
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(pattern PRODUCT-LIKE
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#:attr val PRODUCT-LIKE))
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;; Any -> Bool
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;; recognize isect-descs
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(define (isect-desc? x)
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(member x (list BASE CONTAINER-LIKE PRODUCT-LIKE)))
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;; syntax property key
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;; syntax-transformer value
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(define type-cons-key
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'type-cons)
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;; Identifier -> Bool
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;; check if the type has a syntax property allowing us to create new instances
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(define (reassemblable? t)
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(and (get-type-cons t) #t))
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;; Identifier (Listof Type) -> Type
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;; Create a new instance of the type with the given arguments
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;; needs to have the type-cons-key
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(define (reassemble-type ty args)
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(define tycons (get-type-cons ty))
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(unless tycons
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(error "expected to find type-cons-key"))
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(tycons args)))
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(define-syntax (define-type-constructor+ stx)
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(syntax-parse stx
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[(_ Name:id
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#:arity op arity
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#:arg-variances variances
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#:isect-desc desc:isect-desc
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(~optional (~seq #:extra-info extra-info)))
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#:with Name- (mk-- #'Name)
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#:with NamePat (mk-~ #'Name)
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#:with NamePat- (mk-~ #'Name-)
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#:with mk (format-id #'Name "mk-~a-" (syntax-e #'Name))
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#:with mk- (format-id #'Name- "mk-~a-" (syntax-e #'Name-))
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(quasisyntax/loc stx
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(begin-
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(define-type-constructor- Name-
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#:arity op arity
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#:arg-variances variances
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#,@(if (attribute extra-info)
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#'(#:extra-info extra-info)
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#'()))
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(define-syntax (Name stx)
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(syntax-parse stx
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[(_ t (... ...))
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(syntax/loc stx
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(Name- t (... ...)))]))
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(begin-for-syntax
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(set-type-info! 'Name '#,(attribute desc.val) mk-)
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(define-syntax NamePat
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(pattern-expander
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(syntax-parser
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[(_ p (... ...))
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#'(NamePat- p (... ...))]))))
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(define-for-syntax mk mk-)))]))
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(begin-for-syntax
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;; Syntax -> (Listof Variant)
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;; make a list of the same length as the number of arguments of the given
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;; (type) syntax, all covariant
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(define (mk-covariant ts)
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(for/list ([_ (sequence-tail (in-syntax ts) 1)])
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covariant)))
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;; Define a type constructor that acts like a container:
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;; - covariant
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;; - has an empty element (i.e. intersection always non-empty)
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(define-syntax (define-container-type stx)
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(syntax-parse stx
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[(_ Name:id #:arity op arity
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(~optional (~seq #:extra-info extra-info)))
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(quasisyntax/loc stx
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(define-type-constructor+ Name
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#:arity op arity
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#:arg-variances mk-covariant
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#:isect-desc CONTAINER-LIKE
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#,@(if (attribute extra-info)
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#'(#:extra-info extra-info)
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#'())))]))
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;; Define a type constructor that acts like a container:
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;; - covariant
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;; - does not have an empty element (i.e. intersection may be empty)
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(define-syntax (define-product-type stx)
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(syntax-parse stx
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[(_ Name:id #:arity op arity
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(~optional (~seq #:extra-info extra-info)))
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(quasisyntax/loc stx
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(define-type-constructor+ Name
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#:arity op arity
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#:arg-variances mk-covariant
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#:isect-desc PRODUCT-LIKE
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#,@(if (attribute extra-info)
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#'(#:extra-info extra-info)
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#'())))]))
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(define-binding-type Role #:arity >= 0 #:bvs = 1)
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(define-type-constructor Shares #:arity = 1)
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(define-type-constructor Sends #:arity = 1)
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(define-type-constructor Realizes #:arity = 1)
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(define-type-constructor Reacts #:arity >= 1)
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(define-type-constructor Asserted #:arity = 1)
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(define-type-constructor Retracted #:arity = 1)
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(define-type-constructor Know #:arity = 1)
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(define-type-constructor Forget #:arity = 1)
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(define-product-type Realize #:arity = 1)
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(define-type-constructor Stop #:arity >= 1)
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(define-type-constructor Field #:arity = 1)
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(define-type-constructor Bind #:arity = 1)
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;; keep track of branches for facet effects
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;; (Branch (Listof (Listof Type)))
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(define-type-constructor Branch #:arity >= 0)
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;; sequence of effects
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(define-type-constructor Effs #:arity >= 0)
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(define-base-types OnStart OnStop OnDataflow MakesField)
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(define-for-syntax field-prop-name 'fields)
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(define-type-constructor Actor #:arity = 1)
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#;(define-product-type Message #:arity = 1)
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(define-product-type Tuple #:arity >= 0)
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#;(define-product-type Observe #:arity = 1)
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#;(define-product-type Inbound #:arity = 1)
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#;(define-product-type Outbound #:arity = 1)
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(define-container-type AssertionSet #:arity = 1)
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(define-container-type Patch #:arity = 2)
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;; functions and type abstractions
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(define-binding-type ∀)
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(define-type-constructor → #:arity > 0)
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;; for describing the RHS
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;; a value and a description of the effects
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(define-type-constructor Computation #:arity = 4)
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(define-type-constructor Value #:arity = 1)
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(define-type-constructor Endpoints #:arity >= 0)
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(define-type-constructor Roles #:arity >= 0)
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(define-type-constructor Spawns #:arity >= 0)
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(define-base-types Discard ★/t FacetName)
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(define-for-syntax (type-eval t)
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((current-type-eval) t))
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(define-type-constructor U* #:arity >= 0)
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;; τ.norm in 1st case causes "not valid type" error when referring to ⊥ in another file.
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;; however, this version expands the type at every reference, incurring a potentially large
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;; overhead---2x in the case of book-club.rkt
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;; (copied from ext-stlc example)
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(define-syntax define-type-alias
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(syntax-parser
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[(_ alias:id τ)
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#'(define-syntax- alias
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(make-variable-like-transformer #'τ))]
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[(_ (f:id x:id ...) ty)
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#'(define-syntax- (f stx)
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(syntax-parse stx
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[(_ x ...)
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#:with τ:any-type #'ty
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#'τ.norm]))]))
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(define-type-alias ⊥ (U*))
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(define-type-alias Unit (Tuple))
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(define-for-syntax (prune+sort tys)
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(stx-sort
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(filter-maximal
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(stx->list tys)
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typecheck?)))
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;; (SyntaxListof Type) -> Type
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;; The input types are already expanded/normalized
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;; avoids namespace module mismatch issue in some cases
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(define-for-syntax (mk-U- tys)
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(define tys- (prune+sort tys))
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(if (= 1 (stx-length tys-))
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(stx-car tys-)
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(mk-U*- tys-)))
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(define-syntax (U stx)
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(syntax-parse stx
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[(_ . tys)
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;; canonicalize by expanding to U*, with only (sorted and pruned) leaf tys
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#:with ((~or (~U* ty1- ...) ty2-) ...) (stx-map (current-type-eval) #'tys)
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#:with tys- (prune+sort #'(ty1- ... ... ty2- ...))
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(if (= 1 (stx-length #'tys-))
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(stx-car #'tys-)
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(syntax/loc stx (U* . tys-)))]))
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(define-simple-macro (→fn ty-in ... ty-out)
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(→ ty-in ... (Computation (Value ty-out)
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(Endpoints)
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(Roles)
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(Spawns))))
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(begin-for-syntax
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(define-syntax ~Base
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(pattern-expander
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(syntax-parser
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[(_ nm:id)
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#'((~literal #%plain-app) nm)])))
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(define-syntax ~→fn
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(pattern-expander
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(syntax-parser
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[(_ ty-in:id ... ty-out)
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#'(~→ ty-in ... (~Computation (~Value ty-out)
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(~Endpoints)
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(~Roles)
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(~Spawns)))])))
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;; matching possibly polymorphic types
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(define-syntax ~?∀
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(pattern-expander
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(lambda (stx)
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(syntax-case stx ()
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[(?∀ vars-pat body-pat)
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#'(~or (~∀ vars-pat body-pat)
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(~and (~not (~∀ _ _))
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(~parse vars-pat #'())
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body-pat))])))))
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;; shorthand for writing function types
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(define-syntax-parser proc
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[(_ (~optional (~seq #:forall (X:id ...)))
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ty-in ...
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(~or (~datum ->) (~datum →))
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ty-out
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(~or (~optional (~seq #:spawns (s ...+)))
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(~optional (~seq #:roles (r ...+)))
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(~optional (~seq #:endpoints (e ...+))))
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...)
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#:with spawns (if (attribute s) #'(s ...) #'())
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#:with roles (if (attribute r) #'(r ...) #'())
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#:with endpoints (if (attribute e) #'(e ...) #'())
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#:with body #`(→ ty-in ... (Computation (Value ty-out)
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(Endpoints #,@#'endpoints)
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(Roles #,@#'roles)
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(Spawns #,@#'spawns)))
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(if (attribute X)
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#'(∀ (X ...) body)
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#'body)])
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(begin-for-syntax
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(define-syntax ~proc
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(pattern-expander
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(syntax-parser
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[(_ (~optional (~seq #:forall (X:id ...)))
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ty-in ...
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(~or (~datum ->) (~datum →))
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ty-out
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(~or (~optional (~seq #:spawns s))
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(~optional (~seq #:roles r))
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(~optional (~seq #:endpoints e)))
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...)
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#:with spawns (if (attribute s) #'(s) #'())
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#:with roles (if (attribute r) #'(r) #'())
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#:with endpoints (if (attribute e) #'(e) #'())
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#:with body #`(~→ ty-in ... (~Computation (~Value ty-out)
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(~Endpoints #,@#'endpoints)
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(~Roles #,@#'roles)
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(~Spawns #,@#'spawns)))
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(if (attribute X)
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#'(~∀ (X ...) body)
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#'body)]))))
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|
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;; for looking at the "effects"
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(begin-for-syntax
|
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(define-syntax ~effs
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(pattern-expander
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(syntax-parser
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[(_ eff:id ...)
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#:with tmp (generate-temporary 'effss)
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#'(~and tmp
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(~parse (eff ...) (stx-or #'tmp #'())))])))
|
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|
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(define (stx-truth? a)
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(and a (not (and (syntax? a) (false? (syntax-e a))))))
|
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(define (stx-or a b)
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(cond [(stx-truth? a) a]
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[else b])))
|
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|
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
||
;; User Defined Types, aka Constructors
|
||
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
||
|
||
(begin-for-syntax
|
||
(define-splicing-syntax-class type-constructor-decl
|
||
(pattern (~seq #:type-constructor TypeCons:id))
|
||
(pattern (~seq) #:attr TypeCons #f))
|
||
|
||
(struct user-ctor (typed-ctor untyped-ctor type-tag)
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#:property prop:procedure
|
||
(lambda (v stx)
|
||
(define transformer (user-ctor-typed-ctor v))
|
||
(syntax-parse stx
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||
[(_ e ...)
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||
(quasisyntax/loc stx
|
||
(#,transformer e ...))]))))
|
||
|
||
(define-syntax (define-constructor* stx)
|
||
(syntax-parse stx
|
||
#:datum-literals (:)
|
||
[(_ (Cons:id : TyCons:id slot:id ...) clause ...)
|
||
#'(define-constructor (Cons slot ...)
|
||
#:type-constructor TyCons
|
||
clause ...)]))
|
||
|
||
(define-syntax (define-constructor stx)
|
||
(syntax-parse stx
|
||
[(_ (Cons:id slot:id ...)
|
||
ty-cons:type-constructor-decl
|
||
(~seq #:with
|
||
Alias AliasBody) ...)
|
||
#:with TypeCons (or (attribute ty-cons.TypeCons) (format-id stx "~a/t" (syntax-e #'Cons)))
|
||
#:with MakeTypeCons (format-id #'TypeCons "make-~a" #'TypeCons)
|
||
#:with GetTypeParams (format-id #'TypeCons "get-~a-type-params" #'TypeCons)
|
||
#:with TypeConsExpander (format-id #'TypeCons "~~~a" #'TypeCons)
|
||
#:with TypeConsExtraInfo (format-id #'TypeCons "~a-extra-info" #'TypeCons)
|
||
#:with (StructName Cons- type-tag) (generate-temporaries #'(Cons Cons Cons))
|
||
(define arity (stx-length #'(slot ...)))
|
||
#`(begin-
|
||
(struct- StructName (slot ...) #:reflection-name 'Cons #:transparent)
|
||
(define-syntax (TypeConsExtraInfo stx)
|
||
(syntax-parse stx
|
||
[(_ X (... ...)) #'(#%app- 'type-tag 'MakeTypeCons 'GetTypeParams)]))
|
||
(define-product-type TypeCons
|
||
#:arity = #,arity
|
||
#:extra-info 'TypeConsExtraInfo)
|
||
(define-syntax (MakeTypeCons stx)
|
||
(syntax-parse stx
|
||
[(_ t (... ...))
|
||
#:fail-unless (= #,arity (stx-length #'(t (... ...)))) "arity mismatch"
|
||
#'(TypeCons t (... ...))]))
|
||
(define-syntax (GetTypeParams stx)
|
||
(syntax-parse stx
|
||
[(_ (TypeConsExpander t (... ...)))
|
||
#'(t (... ...))]))
|
||
(define-syntax Cons
|
||
(user-ctor #'Cons- #'StructName 'type-tag))
|
||
(define-typed-syntax (Cons- e (... ...)) ≫
|
||
#:fail-unless (= #,arity (stx-length #'(e (... ...)))) "arity mismatch"
|
||
[⊢ e ≫ e- (⇒ : τ)] (... ...)
|
||
#:fail-unless (all-pure? #'(e- (... ...))) "expressions must be pure"
|
||
----------------------
|
||
[⊢ (#%app- StructName e- (... ...)) (⇒ : (TypeCons τ (... ...)))])
|
||
(define-type-alias Alias AliasBody) ...)]))
|
||
|
||
;; (require-struct chicken #:as Chicken #:from "some-mod.rkt") will
|
||
;; - extract the struct-info for chicken, and ensure that it is immutable, has a set number of fields
|
||
;; - determine the number of slots, N, chicken has
|
||
;; - define the type constructor (Chicken ...N), with the extra info used by define-constructor above
|
||
;; - define chicken+, a turnstile type rule that checks uses of chicken
|
||
;; - bind chicken to a user-ctor struct
|
||
;; TODO: this implementation shares a lot with that of define-constructor
|
||
(define-syntax (require-struct stx)
|
||
(syntax-parse stx
|
||
[(_ ucons:id #:as ty-cons:id #:from lib)
|
||
(with-syntax* ([TypeCons #'ty-cons]
|
||
[MakeTypeCons (format-id #'TypeCons "make-~a" #'TypeCons)]
|
||
[GetTypeParams (format-id #'TypeCons "get-~a-type-params" #'TypeCons)]
|
||
[TypeConsExpander (format-id #'TypeCons "~~~a" #'TypeCons)]
|
||
[TypeConsExtraInfo (format-id #'TypeCons "~a-extra-info" #'TypeCons)]
|
||
[Cons- (format-id #'ucons "~a/checked" #'ucons)]
|
||
[orig-struct-info (generate-temporary #'ucons)]
|
||
[type-tag (generate-temporary #'ucons)])
|
||
(quasisyntax/loc stx
|
||
(begin-
|
||
(require- (only-in- lib [ucons orig-struct-info]))
|
||
(begin-for-syntax
|
||
(define info (syntax-local-value #'orig-struct-info))
|
||
(unless (struct-info? info)
|
||
(raise-syntax-error #f "expected struct" #'#,stx #'ucons))
|
||
(match-define (list desc cons pred accs muts sup) (extract-struct-info info))
|
||
(when (false? (last accs))
|
||
(raise-syntax-error #f "number of slots must be exact" #'#,stx #'ucons))
|
||
(unless (equal? #t sup)
|
||
(raise-syntax-error #f "structs with super-type not supported" #'#,stx #'ucons))
|
||
(define arity (length accs)))
|
||
(define-syntax (TypeConsExtraInfo stx)
|
||
(syntax-parse stx
|
||
[(_ X (... ...)) #'(#%app- 'type-tag 'MakeTypeCons 'GetTypeParams)]))
|
||
(define-product-type TypeCons
|
||
;; issue: arity needs to parse as an exact-nonnegative-integer
|
||
;; fix: check arity in MakeTypeCons
|
||
#:arity >= 0
|
||
#:extra-info 'TypeConsExtraInfo)
|
||
(define-syntax (MakeTypeCons stx)
|
||
(syntax-parse stx
|
||
[(_ t (... ...))
|
||
#:fail-unless (= arity (stx-length #'(t (... ...)))) "arity mismatch"
|
||
#'(TypeCons t (... ...))]))
|
||
(define-syntax (GetTypeParams stx)
|
||
(syntax-parse stx
|
||
[(_ (TypeConsExpander t (... ...)))
|
||
#'(t (... ...))]))
|
||
(define-typed-syntax (Cons- e (... ...)) ≫
|
||
#:fail-unless (= arity (stx-length #'(e (... ...)))) "arity mismatch"
|
||
[⊢ e ≫ e- (⇒ : τ)] (... ...)
|
||
#:fail-unless (all-pure? #'(e- (... ...))) "expressions must be pure"
|
||
----------------------
|
||
[⊢ (#%app- orig-struct-info e- (... ...)) (⇒ : (TypeCons τ (... ...)))])
|
||
(define-syntax ucons
|
||
(user-ctor #'Cons- #'orig-struct-info 'type-tag)))))]))
|
||
|
||
(begin-for-syntax
|
||
(define-syntax ~constructor-extra-info
|
||
(pattern-expander
|
||
(syntax-parser
|
||
[(_ tag mk get)
|
||
#'(_ (_ tag) (_ mk) (_ get))])))
|
||
|
||
(define-syntax ~constructor-type
|
||
(pattern-expander
|
||
(syntax-parser
|
||
[(_ tag . rst)
|
||
#'(~and it
|
||
(~fail #:unless (user-defined-type? #'it))
|
||
(~parse tag (get-type-tag #'it))
|
||
(~Any _ . rst))])))
|
||
|
||
(define-syntax ~constructor-exp
|
||
(pattern-expander
|
||
(syntax-parser
|
||
[(_ cons . rst)
|
||
#'(~and (cons . rst)
|
||
(~fail #:unless (ctor-id? #'cons)))])))
|
||
|
||
(define (inspect t)
|
||
(syntax-parse t
|
||
[(~constructor-type tag t ...)
|
||
(list (syntax-e #'tag) (stx-map type->str #'(t ...)))]))
|
||
|
||
(define (tags-equal? t1 t2)
|
||
(equal? (syntax-e t1) (syntax-e t2)))
|
||
|
||
(define (user-defined-type? t)
|
||
(get-extra-info (type-eval t)))
|
||
|
||
(define (get-type-tag t)
|
||
(syntax-parse (get-extra-info t)
|
||
[(~constructor-extra-info tag _ _)
|
||
(syntax-e #'tag)]))
|
||
|
||
(define (get-type-args t)
|
||
(syntax-parse (get-extra-info t)
|
||
[(~constructor-extra-info _ _ get)
|
||
(define f (syntax-local-value #'get))
|
||
(syntax->list (f #`(get #,t)))]))
|
||
|
||
(define (make-cons-type t args)
|
||
(syntax-parse (get-extra-info t)
|
||
[(~constructor-extra-info _ mk _)
|
||
(define f (syntax-local-value #'mk))
|
||
(type-eval (f #`(mk #,@args)))]))
|
||
|
||
(define (ctor-id? stx)
|
||
(and (identifier? stx)
|
||
(user-ctor? (syntax-local-value stx (const #f)))))
|
||
|
||
(define (untyped-ctor stx)
|
||
(user-ctor-untyped-ctor (syntax-local-value stx (const #f))))
|
||
|
||
;; requires (ctor-id? stx)
|
||
;; fetch the type tag
|
||
(define (ctor-type-tag stx)
|
||
(user-ctor-type-tag (syntax-local-value stx (const #f)))))
|
||
|
||
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
||
;; Require & Provide
|
||
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
||
|
||
;; Import and ascribe a type from an untyped module
|
||
;; TODO: this is where contracts would need to go
|
||
(define-syntax (require/typed stx)
|
||
(syntax-parse stx
|
||
#:datum-literals (:)
|
||
[(_ lib [name:id : ty:type] ...)
|
||
#:with (name- ...) (format-ids "~a-" #'(name ...))
|
||
(syntax/loc stx
|
||
(begin-
|
||
(require (only-in lib [name name-] ...))
|
||
(define-syntax name
|
||
(make-variable-like-transformer (add-orig (assign-type #'name- #'ty #:wrap? #f) #'name)))
|
||
...))]))
|
||
|
||
;; Format identifiers in the same way
|
||
;; FormatString (SyntaxListOf Identifier) -> (Listof Identifier)
|
||
(define-for-syntax (format-ids fmt ids)
|
||
(for/list ([id (in-syntax ids)])
|
||
(format-id id fmt id)))
|
||
|
||
;; (SyntaxListof (SyntaxList Identifier Type Identifier)) -> (Listof Identifier)
|
||
;; For each triple (name- ty name),
|
||
;; assign the ty to name- with the orig name
|
||
(define-for-syntax (assign-types los)
|
||
(for/list ([iti (in-syntax los)])
|
||
(match-define (list name- ty name) (syntax->list iti))
|
||
(add-orig (assign-type name- ty #:wrap? #f) name)))
|
||
|
||
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
||
;; Conveniences
|
||
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
||
|
||
;; (SyntaxListof (SyntaxListof Type)) -> (U (SyntaxListof Branch) #'())
|
||
(define-for-syntax (make-Branch tys*)
|
||
(syntax-parse tys*
|
||
[()
|
||
#'()]
|
||
[(() ...)
|
||
#'()]
|
||
[((ty ...) ...)
|
||
(define effs
|
||
(for/list ([tys (in-syntax tys*)])
|
||
(mk-Effs- (syntax->list tys))))
|
||
#`(#,(mk-Branch- effs))]))
|
||
|
||
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
||
;; Syntax
|
||
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
||
|
||
(require-struct observe #:as Observe #:from syndicate/actor-lang)
|
||
(require-struct inbound #:as Inbound #:from syndicate/actor-lang)
|
||
(require-struct outbound #:as Outbound #:from syndicate/actor-lang)
|
||
(require-struct message #:as Message #:from syndicate/actor-lang)
|
||
|
||
(begin-for-syntax
|
||
|
||
;; constructors with arity one
|
||
(define-syntax-class kons1
|
||
(pattern (~or (~datum observe)
|
||
(~datum inbound)
|
||
(~datum outbound)
|
||
(~datum message))))
|
||
|
||
(define (kons1->constructor stx)
|
||
(syntax-parse stx
|
||
#:datum-literals (observe inbound outbound)
|
||
[observe #'syndicate:observe]
|
||
[inbound #'syndicate:inbound]
|
||
[outbound #'syndicate:outbound]
|
||
[message #'syndicate:message]))
|
||
|
||
(define-syntax-class basic-val
|
||
(pattern (~or boolean
|
||
integer
|
||
string)))
|
||
|
||
(define-syntax-class prim-op
|
||
(pattern (~or (~literal +)
|
||
(~literal -)
|
||
(~literal displayln)))))
|
||
|
||
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
||
;; Utilities Over Types
|
||
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
||
|
||
(define-for-syntax (bot? t)
|
||
((current-typecheck-relation) t (mk-U*- '())))
|
||
|
||
(define-for-syntax bot
|
||
(mk-U*- '()))
|
||
|
||
(define-for-syntax (flat-type? τ)
|
||
(syntax-parse τ
|
||
[(~→ τ ...) #f]
|
||
[(~Actor τ) #f]
|
||
[(~Role (_) _ ...) #f]
|
||
[_ #t]))
|
||
|
||
(define-for-syntax (strip-? t)
|
||
(syntax-parse t
|
||
[(~U* τ ...) (mk-U- (stx-map strip-? #'(τ ...)))]
|
||
[~★/t (type-eval #'★/t)]
|
||
;; since (Observe X) can match (Message X):
|
||
;; doing this specifically for the intersection operation in the spawn rule, need to check other
|
||
;; uses
|
||
[(~Observe τ) (mk-U- (list #'τ (mk-Message- #'(τ))))]
|
||
[_ (mk-U*- '())]))
|
||
|
||
;; similar to strip- fns, but leave non-message types as they are
|
||
(define-for-syntax (prune-message t)
|
||
(syntax-parse t
|
||
[(~U* τ ...) (mk-U- (stx-map prune-message #'(τ ...)))]
|
||
[~★/t (type-eval #'★/t)]
|
||
[(~Message τ) #'τ]
|
||
[_ t]))
|
||
|
||
(define-for-syntax (strip-inbound t)
|
||
(syntax-parse t
|
||
[(~U* τ ...) (mk-U- (stx-map strip-inbound #'(τ ...)))]
|
||
[~★/t (type-eval #'★/t)]
|
||
[(~Inbound τ) #'τ]
|
||
[_ (mk-U*- '())]))
|
||
|
||
(define-for-syntax (strip-outbound t)
|
||
(syntax-parse t
|
||
[(~U* τ ...) (mk-U- (stx-map strip-outbound #'(τ ...)))]
|
||
[~★/t (type-eval #'★/t)]
|
||
[(~Outbound τ) #'τ]
|
||
[_ (mk-U*- '())]))
|
||
|
||
(define-for-syntax (relay-interests t)
|
||
(syntax-parse t
|
||
[(~U* τ ...) (mk-U- (stx-map relay-interests #'(τ ...)))]
|
||
[~★/t (type-eval #'★/t)]
|
||
[(~Observe (~Inbound τ)) (mk-Observe- #'(τ))]
|
||
[_ (mk-U*- '())]))
|
||
|
||
;; (SyntaxOf RoleType ...) -> (Syntaxof InputType OutputType SpawnType)
|
||
(define-for-syntax (analyze-roles rs)
|
||
(define-values (lis los lis/i los/i lss)
|
||
(for/fold ([is '()]
|
||
[os '()]
|
||
[is/i '()]
|
||
[os/i '()]
|
||
[ss '()])
|
||
([r (in-syntax rs)])
|
||
(define-values (i o i/i o/i s) (analyze-role-input/output r))
|
||
(values (cons i is) (cons o os) (cons i/i is/i) (cons o/i os/i) (cons s ss))))
|
||
#`(#,(mk-U- lis)
|
||
#,(mk-U- los)
|
||
#,(mk-U- lis/i)
|
||
#,(mk-U- los/i)
|
||
#,(mk-U- lss)))
|
||
|
||
;; Wanted test case, but can't use it bc it uses things defined for-syntax
|
||
#;(module+ test
|
||
(let ([r (type-eval #'(Role (x) (Shares Int)))])
|
||
(syntax-parse (analyze-role-input/output r)
|
||
[(τ-i τ-o)
|
||
(check-true (type=? #'τ-o (type-eval #'Int)))])))
|
||
|
||
;; RoleType -> (Values ExternalInputType ExternalOutputType
|
||
;; InternalInputType InternalOutputType
|
||
;; SpawnType)
|
||
(define-for-syntax (analyze-role-input/output t)
|
||
(syntax-parse t
|
||
[(~Branch (~Effs τ-r ...) ...)
|
||
#:with (τ-i τ-o τ-i/i τ-o/i τ-a) (analyze-roles #'(τ-r ... ...))
|
||
(values #'τ-i #'τ-o #'τ-i/i #'τ-o/i #'τ-a)]
|
||
[(~Stop name:id τ-r ...)
|
||
#:with (τ-i τ-o τ-i/i τ-o/i τ-a) (analyze-roles #'(τ-r ...))
|
||
(values #'τ-i #'τ-o #'τ-i/i #'τ-o/i #'τ-a)]
|
||
[(~Actor τc)
|
||
(values bot bot bot bot t)]
|
||
[(~Sends τ-m)
|
||
(values bot (mk-Message- #'(τ-m)) bot bot bot)]
|
||
[(~Realizes τ-m)
|
||
(values bot bot bot (mk-Realize- #'(τ-m)) bot)]
|
||
[(~Role (name:id)
|
||
(~or (~Shares τ-s)
|
||
(~Know τ-k)
|
||
(~Sends τ-m)
|
||
(~Realizes τ-rlz)
|
||
(~Reacts τ-if τ-then ...)) ...
|
||
(~and (~Role _ ...) sub-role) ...)
|
||
#:with (msg ...) (for/list ([m (in-syntax #'(τ-m ...))])
|
||
(mk-Message- (list m)))
|
||
#:with (rlz ...) (for/list ([r (in-syntax #'(τ-rlz ...))])
|
||
(mk-Realize- (list r)))
|
||
(define-values (is/e os/e is/i os/i ss)
|
||
(for/fold ([ins '()]
|
||
[outs '()]
|
||
[ins/int '()]
|
||
[outs/int '()]
|
||
[spawns '()])
|
||
([t (in-syntax #'(τ-then ... ... sub-role ...))])
|
||
(define-values (i o i/i o/i s) (analyze-role-input/output t))
|
||
(values (cons i ins) (cons o outs) (cons i/i ins/int) (cons o/i outs/int) (cons s spawns))))
|
||
(define-values (ifs/ext ifs/int) (partition external-evt? (stx->list #'(τ-if ...))))
|
||
(define pat-types/ext (map event-desc-type ifs/ext))
|
||
(define pat-types/int (map event-desc-type ifs/int))
|
||
(values (mk-U- #`(#,@is/e #,@pat-types/ext))
|
||
(mk-U- #`(τ-s ... msg ... #,@os/e #,@(map pattern-sub-type pat-types/ext)))
|
||
(mk-U- #`(#,@is/i #,@pat-types/int))
|
||
(mk-U- #`(τ-k ... rlz ... #,@os/i #,@(map pattern-sub-type pat-types/int)))
|
||
(mk-U- ss))]))
|
||
|
||
;; EventType -> Bool
|
||
;; recognize external events (assertions and messages)
|
||
(define-for-syntax (external-evt? evt)
|
||
(syntax-parse evt
|
||
[(~Asserted τ) #t]
|
||
[(~Retracted τ) #t]
|
||
[(~Message τ) #t]
|
||
[_ #f]))
|
||
|
||
;; EventDescriptorType -> Type
|
||
(define-for-syntax (event-desc-type desc)
|
||
(syntax-parse desc
|
||
[(~Asserted τ) #'τ]
|
||
[(~Retracted τ) #'τ]
|
||
[(~Message τ) desc]
|
||
[(~Know τ) #'τ]
|
||
[(~Forget τ) #'τ]
|
||
[(~Realize τ) desc]
|
||
[_ (mk-U*- '())]))
|
||
|
||
;; PatternType -> Type
|
||
(define-for-syntax (pattern-sub-type pt)
|
||
(syntax-parse pt
|
||
[(~or (~Message τ)
|
||
(~Realize τ))
|
||
(define t (replace-bind-and-discard-with-★ #'τ))
|
||
(mk-Observe- (list t))]
|
||
[τ
|
||
#:when (bot? #'τ)
|
||
#'τ]
|
||
[τ
|
||
(define t (replace-bind-and-discard-with-★ #'τ))
|
||
(mk-Observe- (list t))]))
|
||
|
||
;; TODO : can potentially use something like `subst` for this
|
||
(define-for-syntax (replace-bind-and-discard-with-★ t)
|
||
(syntax-parse t
|
||
[(~Bind _)
|
||
(type-eval #'★/t)]
|
||
[~Discard
|
||
(type-eval #'★/t)]
|
||
[(~U* τ ...)
|
||
(mk-U- (stx-map replace-bind-and-discard-with-★ #'(τ ...)))]
|
||
[(~Any/bvs τ-cons () τ ...)
|
||
#:when (reassemblable? #'τ-cons)
|
||
(define subitems (for/list ([t (in-syntax #'(τ ...))])
|
||
(replace-bind-and-discard-with-★ t)))
|
||
(reassemble-type #'τ-cons subitems)]
|
||
[_ t]))
|
||
|
||
;; Type -> String
|
||
(define-for-syntax (type->strX ty)
|
||
;; Identifier -> String
|
||
;; this won't work for any names with numbers in them :\
|
||
(define (un-gensym x)
|
||
(define GENSYMED #px"^(\\D*)\\d*$")
|
||
(second (regexp-match GENSYMED (symbol->string (syntax-e x)))))
|
||
;; (Listof String) -> String
|
||
(define (paren-join xs)
|
||
(string-join xs
|
||
#:before-first "("
|
||
#:after-last ")"))
|
||
(syntax-parse ty
|
||
[X:id
|
||
(un-gensym #'X)]
|
||
[(~U* τ ...)
|
||
(paren-join (cons "U" (stx-map type->strX #'(τ ...))))]
|
||
[(~Base x)
|
||
(un-gensym #'x)]
|
||
[(~Any/bvs τ-cons (X ...) τ ...)
|
||
(define ctor (un-gensym #'τ-cons))
|
||
(define body (stx-map type->strX #'(τ ...)))
|
||
(define desc
|
||
(cond
|
||
[(empty? (syntax->list #'(X ...)))
|
||
(list* ctor body)]
|
||
[else
|
||
(define vars
|
||
(paren-join (stx-map type->strX #'(X ...))))
|
||
(list* ctor vars body)]))
|
||
(paren-join desc)]))
|
||
|
||
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
||
;; Subtyping and Judgments on Types
|
||
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
||
|
||
(begin-for-syntax
|
||
(define trace-sub? (make-parameter #f))
|
||
|
||
;; Type Type -> Bool
|
||
;; subtyping
|
||
(define (<: t1 t2)
|
||
(when (trace-sub?)
|
||
(printf "~a\n<:\n~a\n" t1 t2))
|
||
(syntax-parse #`(#,t1 #,t2)
|
||
[(_ ~★/t)
|
||
(flat-type? t1)]
|
||
[((~U* τ1 ...) _)
|
||
(stx-andmap (lambda (t) (<: t t2)) #'(τ1 ...))]
|
||
[(_ (~U* τ2:type ...))
|
||
(stx-ormap (lambda (t) (<: t1 t)) #'(τ2 ...))]
|
||
[((~Actor τ1) (~Actor τ2))
|
||
(and (<: #'τ1 #'τ2)
|
||
(<: (∩ (strip-? #'τ1) #'τ2) #'τ1))]
|
||
[((~proc τ-in1 ... -> τ-out1 #:spawns (~seq S1 ...)
|
||
#:roles (~seq R1 ...)
|
||
#:endpoints (~seq E1 ...))
|
||
(~proc τ-in2 ... -> τ-out2 #:spawns (~seq S2 ...)
|
||
#:roles (~seq R2 ...)
|
||
#:endpoints (~seq E2 ...)))
|
||
(and (stx-length=? #'(τ-in1 ...) #'(τ-in2 ...))
|
||
(stx-andmap <: #'(τ-in2 ...) #'(τ-in1 ...))
|
||
(<: #'τ-out1 #'τ-out2)
|
||
(<: (mk-Actor- (list (mk-U*- #'(S1 ...))))
|
||
(mk-Actor- (list (mk-U*- #'(S2 ...)))))
|
||
(<: (mk-U*- #'(R1 ...))
|
||
(mk-U*- #'(R2 ...)))
|
||
(<: (mk-U*- #'(E1 ...))
|
||
(mk-U*- #'(E2 ...))))]
|
||
[(~Discard _)
|
||
#t]
|
||
[(X:id Y:id)
|
||
(free-identifier=? #'X #'Y)]
|
||
[((~∀ (X:id ...) τ1) (~∀ (Y:id ...) τ2))
|
||
#:when (stx-length=? #'(X ...) #'(Y ...))
|
||
#:with τ2-X/Y (substs #'(X ...) #'(Y ...) #'τ2)
|
||
(<: #'τ1 #'τ2-X/Y)]
|
||
[((~Base τ1:id) (~Base τ2:id))
|
||
(free-identifier=? #'τ1 #'τ2)]
|
||
[((~Role (x) _ ...) (~Role (y) _ ...))
|
||
;; Extremely Coarse subtyping for Role types
|
||
(type=? t1 t2)]
|
||
;; TODO: clauses for Roles, effectful functions, and so on
|
||
[((~Any/bvs τ-cons1 () τ1 ...) (~Any/bvs τ-cons2 () τ2 ...))
|
||
#:when (free-identifier=? #'τ-cons1 #'τ-cons2)
|
||
#:do [(define variances (syntax-property #'τ-cons1 'arg-variances))]
|
||
#:when variances
|
||
#:when (stx-length=? #'(τ1 ...) #'(τ2 ...))
|
||
(for/and ([ty1 (in-syntax #'(τ1 ...))]
|
||
[ty2 (in-syntax #'(τ2 ...))]
|
||
[var (in-list variances)])
|
||
(match var
|
||
[(== covariant)
|
||
(<: ty1 ty2)]
|
||
[(== contravariant)
|
||
(<: ty2 ty1)]
|
||
[(== invariant)
|
||
(and (<: ty1 ty2)
|
||
(<: ty2 ty1))]
|
||
[(== irrelevant)
|
||
#t]))]
|
||
[_
|
||
#f]))
|
||
|
||
;; shortcuts for mapping
|
||
(define ((<:l l) r)
|
||
(<: l r))
|
||
|
||
(define ((<:r r) l)
|
||
(<: l r)))
|
||
|
||
;; !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
|
||
;; MODIFYING GLOBAL TYPECHECKING STATE!!!!!
|
||
;; !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
|
||
|
||
(begin-for-syntax
|
||
(current-typecheck-relation <:))
|
||
|
||
;; Flat-Type Flat-Type -> Type
|
||
;; Intersection
|
||
(define-for-syntax (∩ t1 t2)
|
||
(unless (and (flat-type? t1) (flat-type? t2))
|
||
(error '∩ "expected two flat-types"))
|
||
(syntax-parse #`(#,t1 #,t2)
|
||
[(_ ~★/t)
|
||
t1]
|
||
[(~★/t _)
|
||
t2]
|
||
[((~U* τ1:type ...) _)
|
||
(mk-U- (stx-map (lambda (t) (∩ t t2)) #'(τ1 ...)))]
|
||
[(_ (~U* τ2:type ...))
|
||
(mk-U- (stx-map (lambda (t) (∩ t1 t)) #'(τ2 ...)))]
|
||
[(X:id Y:id)
|
||
#:when (free-identifier=? #'X #'Y)
|
||
#'X]
|
||
;; Also, using <: is OK, even though <: refers to ∩, because <:'s use of ∩ is only
|
||
;; in the Actor case.
|
||
[((~Base τ1:id) (~Base τ2:id))
|
||
#:when (free-identifier=? #'τ1 #'τ2)
|
||
t1]
|
||
[((~Any/bvs τ-cons1 () τ1 ...) (~Any/bvs τ-cons2 () τ2 ...))
|
||
#:when (free-identifier=? #'τ-cons1 #'τ-cons2)
|
||
#:when (stx-length=? #'(τ1 ...) #'(τ2 ...))
|
||
#:do [(define desc (get-type-isec-desc #'τ-cons1))]
|
||
#:when desc
|
||
(define slots (stx-map ∩ #'(τ1 ...) #'(τ2 ...)))
|
||
(match desc
|
||
[(== BASE)
|
||
(error "this isn't right")]
|
||
[(== CONTAINER-LIKE)
|
||
(reassemble-type #'τ-cons1 slots)]
|
||
[(== PRODUCT-LIKE)
|
||
(if (ormap bot? slots)
|
||
(mk-U*- '())
|
||
(reassemble-type #'τ-cons1 slots))])]
|
||
[_ (mk-U*- '())]))
|
||
|
||
;; Type Type -> Bool
|
||
;; first type is the contents of the set/dataspace
|
||
;; second type is the type of a pattern
|
||
(define-for-syntax (project-safe? t1 t2)
|
||
(define (project-safe* t1 t2)
|
||
(syntax-parse #`(#,t1 #,t2)
|
||
[(_ (~Bind τ2))
|
||
(and (finite? t1) (<: t1 #'τ2))]
|
||
[(_ ~Discard)
|
||
#t]
|
||
[(_ ~★/t)
|
||
#t]
|
||
[((~U* τ1:type ...) _)
|
||
(stx-andmap (lambda (t) (project-safe? t t2)) #'(τ1 ...))]
|
||
[(_ (~U* τ2:type ...))
|
||
(stx-andmap (lambda (t) (project-safe? t1 t)) #'(τ2 ...))]
|
||
[((~Any/bvs τ-cons1 () τ1 ...) (~Any/bvs τ-cons2 () τ2 ...))
|
||
#:when (free-identifier=? #'τ-cons1 #'τ-cons2)
|
||
#:when (stx-length=? #'(τ1 ...) #'(τ2 ...))
|
||
#:do [(define desc (get-type-isec-desc #'τ-cons1))]
|
||
#:when (equal? desc PRODUCT-LIKE)
|
||
(stx-andmap project-safe? #'(τ1 ...) #'(τ2 ...))]
|
||
[_ #t]))
|
||
(if (overlap? t1 t2)
|
||
(project-safe* t1 t2)
|
||
#t))
|
||
|
||
;; AssertionType PatternType -> Bool
|
||
;; Is it possible for things of these two types to match each other?
|
||
;; Flattish-Type = Flat-Types + ★/t, Bind, Discard (assertion and pattern types)
|
||
(define-for-syntax (overlap? t1 t2)
|
||
(define t22 (replace-bind-and-discard-with-★ t2))
|
||
(not (<: (∩ t1 t22) (mk-U*- '()))))
|
||
|
||
;; Flattish-Type -> Bool
|
||
(define-for-syntax (finite? t)
|
||
(syntax-parse t
|
||
[~★/t #f]
|
||
[(~U* τ:type ...)
|
||
(stx-andmap finite? #'(τ ...))]
|
||
[X:id
|
||
#t]
|
||
[(~Base _) #t]
|
||
[(~Any/bvs τ-cons (X ...) τ ...)
|
||
(stx-andmap finite? #'(τ ...))]))
|
||
|
||
;; PatternType -> Type
|
||
(define-for-syntax (pattern-matching-assertions t)
|
||
(syntax-parse t
|
||
[(~Bind τ)
|
||
#'τ]
|
||
[~Discard
|
||
(type-eval #'★/t)]
|
||
[(~U* τ ...)
|
||
(mk-U- (stx-map pattern-matching-assertions #'(τ ...)))]
|
||
[(~Any/bvs τ-cons () τ ...)
|
||
#:when (reassemblable? #'τ-cons)
|
||
(define subitems (for/list ([t (in-syntax #'(τ ...))])
|
||
(pattern-matching-assertions t)))
|
||
(reassemble-type #'τ-cons subitems)]
|
||
[_ t]))
|
||
|
||
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
||
;; Effect Checking
|
||
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
||
|
||
;; DesugaredSyntax EffectName -> (Syntaxof Effect ...)
|
||
(define-for-syntax (get-effect e- eff)
|
||
(or (syntax-property e- eff) #'()))
|
||
|
||
;; DesugaredSyntax EffectName -> Bool
|
||
(define-for-syntax (effect-free? e- eff)
|
||
(define prop (syntax-property e- eff))
|
||
(or (false? prop) (stx-null? prop)))
|
||
|
||
;; DesugaredSyntax -> Bool
|
||
(define-for-syntax (pure? e-)
|
||
(for/and ([key (in-list '(ν-ep ν-f ν-s))])
|
||
(effect-free? e- key)))
|
||
|
||
;; (SyntaxOf DesugaredSyntax ...) -> Bool
|
||
(define-for-syntax (all-pure? es)
|
||
(stx-andmap pure? es))
|
||
|
||
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
||
;; Lambdas
|
||
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
||
|
||
(define-typed-syntax (lambda ([x:id (~optional (~datum :)) τ:type] ...) body ...+) ≫
|
||
[[x ≫ x- : τ] ... ⊢ (begin body ...) ≫ body- (⇒ : τ-e)
|
||
(⇒ ν-ep (~effs τ-ep ...))
|
||
(⇒ ν-s (~effs τ-s ...))
|
||
(⇒ ν-f (~effs τ-f ...))]
|
||
----------------------------------------
|
||
[⊢ (lambda- (x- ...) body-) (⇒ : (→ τ ... (Computation (Value τ-e)
|
||
(Endpoints τ-ep ...)
|
||
(Roles τ-f ...)
|
||
(Spawns τ-s ...))))])
|
||
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
||
;; Type Abstraction
|
||
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
||
|
||
(define-typed-syntax (Λ (tv:id ...) e) ≫
|
||
[([tv ≫ tv- :: #%type] ...) () ⊢ e ≫ e- ⇒ τ]
|
||
--------
|
||
;; can't use internal mk-∀- constructor here
|
||
;; - will cause the bound-id=? quirk to show up
|
||
;; (when subsequent tyvar refs are expanded with `type` stx class)
|
||
;; - requires converting type= and subst to use free-id=?
|
||
;; (which is less performant)
|
||
[⊢ e- ⇒ (∀ (tv- ...) τ)])
|
||
|
||
(define-typed-syntax inst
|
||
[(_ e τ:type ...) ≫
|
||
#:cut
|
||
[⊢ e ≫ e- ⇒ (~∀ tvs τ_body)]
|
||
#:fail-unless (stx-andmap instantiable? #'tvs #'(τ.norm ...))
|
||
"types must be instantiable"
|
||
#:fail-unless (pure? #'e-) "expression must be pure"
|
||
--------
|
||
[⊢ e- ⇒ #,(substs #'(τ.norm ...) #'tvs #'τ_body)]]
|
||
[(_ e) ≫ --- [≻ e]])
|
||
|
||
;; Identifier Type -> Bool
|
||
;; determine if a type is suitable for instantiating a variable
|
||
;; only row variables may be instantiated with effectful/higher-order types
|
||
(define-for-syntax (instantiable? x ty)
|
||
(or (row-variable? x)
|
||
(and (flat-type? ty)
|
||
(finite? ty))))
|
||
|
||
(begin-for-syntax
|
||
;; CONVENTION: Type variables for effects are prefixed with ρ
|
||
(define (row-variable? x)
|
||
(and (identifier? x)
|
||
(char=? (string-ref (symbol->string (syntax-e x)) 0) #\ρ)))
|
||
|
||
(define-syntax-class row-id
|
||
#:attributes ()
|
||
(pattern x:id #:when (row-variable? #'x))))
|
||
|
||
;; instantiate row variables with types from procedure arguments
|
||
;; BRITTLE?
|
||
(define-typed-syntax (call/inst e:expr args:expr ...) ≫
|
||
[⊢ e ≫ e- (⇒ : (~∀ (X:row-id ...) τ))]
|
||
[⊢ args ≫ args- (⇒ : τ-a)] ...
|
||
#:fail-unless (all-pure? #'(e- args- ...))
|
||
"expressions must be pure"
|
||
;; ordering pretty arbitrary
|
||
#:with ((~or (~proc _ ... -> _
|
||
#:spawns (~seq S ...)
|
||
#:roles (~seq R ...)
|
||
#:endpoints (~seq E ...))
|
||
_) ...) #'(τ-a ...)
|
||
#:with (SS ...) (if (attribute S) #'(S ... ...) #'())
|
||
#:with (RR ...) (if (attribute R) #'(R ... ...) #'())
|
||
#:with (EE ...) (if (attribute E) #'(E ... ...) #'())
|
||
#:fail-unless (stx-length=? #'(X ...) #'(SS ... RR ... EE ...))
|
||
"found the wrong number of effects"
|
||
-------------------------------------------------------
|
||
[≻ ((inst e- SS ... RR ... EE ...) args- ...)])
|
||
|
||
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
||
;; Sequencing & Definitions
|
||
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
||
|
||
;; For Debugging
|
||
(define-for-syntax DEBUG-BINDINGS? #f)
|
||
|
||
(define-for-syntax (int-def-ctx-bind-type-rename x x- t ctx)
|
||
(when DEBUG-BINDINGS?
|
||
(printf "adding to context ~a\n" (syntax-debug-info x)))
|
||
(syntax-local-bind-syntaxes (list x-) #f ctx)
|
||
(syntax-local-bind-syntaxes (list x)
|
||
#`(make-rename-transformer
|
||
(add-orig (assign-type #'#,x- #'#,t #:wrap? #f) #'#,x))
|
||
ctx))
|
||
|
||
(define-for-syntax (add-bindings-to-ctx e- def-ctx)
|
||
(syntax-parse e-
|
||
#:literals (erased field/intermediate define/intermediate begin-)
|
||
[(erased (field/intermediate (x:id x-:id τ e-) ...))
|
||
(for ([orig-name (in-syntax #'(x ... ))]
|
||
[new-name (in-syntax #'(x- ...))]
|
||
[field-ty (in-syntax #'(τ ...))])
|
||
(int-def-ctx-bind-type-rename orig-name new-name field-ty def-ctx))]
|
||
[(erased (define/intermediate x:id x-:id τ e-))
|
||
(int-def-ctx-bind-type-rename #'x #'x- #'τ def-ctx)]
|
||
#;[(erased (begin- e ...))
|
||
(for ([e (in-syntax #'(e ...))])
|
||
(add-bindings-to-ctx e def-ctx))]
|
||
[_ (void)]))
|
||
|
||
(define-for-syntax (display-ctx-bindings ctx)
|
||
(printf "context:\n")
|
||
(for ([x (in-list (internal-definition-context-binding-identifiers ctx))])
|
||
(printf ">>~a\n" (syntax-debug-info x))))
|
||
|
||
;; -> (Values e-... (Listof Type) (Listof EndpointEffects) (Listof FacetEffects) (Listof SpawnEffects))
|
||
;; recognizes local binding forms
|
||
;; (field/intermediate [x e] ...
|
||
;; (define/intermediate x x- τ e)
|
||
(define-for-syntax (walk/bind e...
|
||
[def-ctx (syntax-local-make-definition-context)]
|
||
[unique (gensym 'walk/bind)])
|
||
(define-values (rev-e-... rev-τ... ep-effects facet-effects spawn-effects)
|
||
(let loop ([e... (syntax->list e...)]
|
||
[rev-e-... '()]
|
||
[rev-τ... '()]
|
||
[ep-effects '()]
|
||
[facet-effects '()]
|
||
[spawn-effects '()])
|
||
(match e...
|
||
['()
|
||
(values rev-e-... rev-τ... ep-effects facet-effects spawn-effects)]
|
||
[(cons e more)
|
||
(when (and DEBUG-BINDINGS?
|
||
(identifier? e))
|
||
(display-ctx-bindings def-ctx)
|
||
(printf "expanding ~a\n" (syntax-debug-info e)))
|
||
(define e- (local-expand e (list unique) (list #'erased #'begin) def-ctx))
|
||
(syntax-parse e-
|
||
#:literals (begin)
|
||
[(begin e ...)
|
||
(loop (append (syntax->list #'(e ...)) more)
|
||
rev-e-...
|
||
rev-τ...
|
||
ep-effects
|
||
facet-effects
|
||
spawn-effects)]
|
||
[_
|
||
(define τ (syntax-property e- ':))
|
||
(define-values (ep-effs f-effs s-effs)
|
||
(values (syntax->list (get-effect e- 'ν-ep))
|
||
(syntax->list (get-effect e- 'ν-f))
|
||
(syntax->list (get-effect e- 'ν-s))))
|
||
(add-bindings-to-ctx e- def-ctx)
|
||
(loop more
|
||
(cons e- rev-e-...)
|
||
(cons τ rev-τ...)
|
||
(append ep-effs ep-effects)
|
||
(append f-effs facet-effects)
|
||
(append s-effs spawn-effects))])])))
|
||
(values (reverse rev-e-...)
|
||
(reverse rev-τ...)
|
||
ep-effects
|
||
facet-effects
|
||
spawn-effects))
|
||
|
||
(define-syntax (field/intermediate stx)
|
||
(syntax-parse stx
|
||
[(_ [x:id x-:id τ e-] ...)
|
||
#'(syndicate:field [x- e-] ...)]))
|
||
|
||
|
||
(define-syntax (define/intermediate stx)
|
||
(syntax-parse stx
|
||
[(_ x:id x-:id τ e)
|
||
;; including a syntax binding for x allows for module-top-level references
|
||
;; (where walk/bind won't replace further uses) and subsequent provides
|
||
#'(begin-
|
||
(define-syntax x
|
||
(make-variable-like-transformer (add-orig (assign-type #'x- #'τ #:wrap? #f) #'x)))
|
||
(define- x- e))]))
|
||
|
||
;; copied from ext-stlc
|
||
(define-typed-syntax define
|
||
[(_ x:id (~datum :) τ:type e:expr) ≫
|
||
[⊢ e ≫ e- ⇐ τ.norm]
|
||
#:fail-unless (pure? #'e-) "expression must be pure"
|
||
#:with x- (generate-temporary #'x)
|
||
#:with x+ (syntax-local-identifier-as-binding #'x)
|
||
--------
|
||
[⊢ (define/intermediate x+ x- τ.norm e-) (⇒ : ★/t)]]
|
||
[(_ x:id e) ≫
|
||
;This won't work with mutually recursive definitions
|
||
[⊢ e ≫ e- ⇒ τ]
|
||
#:fail-unless (pure? #'e-) "expression must be pure"
|
||
#:with x- (generate-temporary #'x)
|
||
#:with x+ (syntax-local-identifier-as-binding #'x)
|
||
--------
|
||
[⊢ (define/intermediate x+ x- τ e-) (⇒ : ★/t)]]
|
||
[(_ (f [x (~optional (~datum :)) ty:type] ...
|
||
(~or (~datum →) (~datum ->)) ty_out:type)
|
||
e ...+) ≫
|
||
[⊢ (lambda ([x : ty] ...) (begin e ...)) ≫ e- (⇒ : (~and fun-ty
|
||
(~→ (~not (~Computation _ ...)) ...
|
||
(~Computation (~Value τ-v)
|
||
_ ...))))]
|
||
#:fail-unless (<: #'τ-v #'ty_out.norm)
|
||
(format "expected different return type\n got ~a\n expected ~a\n"
|
||
#'τ-v #'ty_out
|
||
#;(type->str #'τ-v)
|
||
#;(type->str #'ty_out))
|
||
#:with f- (add-orig (generate-temporary #'f) #'f)
|
||
--------
|
||
[⊢ (define/intermediate f f- fun-ty e-) (⇒ : ★/t)]]
|
||
[(_ (f [x (~optional (~datum :)) ty] ...)
|
||
e ...+) ≫
|
||
----------------------------
|
||
[≻ (define (f [x ty] ... -> ★/t) e ...)]]
|
||
;; Polymorphic definitions
|
||
[(_ ((~datum ∀) (X:id ...)
|
||
(f [x (~optional (~datum :)) ty] ...
|
||
(~or (~datum →) (~datum ->)) ty_out))
|
||
e ...+) ≫
|
||
#:with e+ #'(Λ (X ...)
|
||
(lambda ([x : ty] ...)
|
||
(begin e ...)))
|
||
[[X ≫ X- :: #%type] ... ⊢ e+ ≫ e-
|
||
(⇒ : (~and res-ty
|
||
(~∀ (Y ...)
|
||
(~→ (~not (~Computation _ ...)) ...
|
||
(~Computation (~Value τ-v)
|
||
_ ...)))))]
|
||
#:fail-unless (<: (type-eval #'(∀ (Y ...) τ-v))
|
||
(type-eval #'(∀ (X ...) ty_out)))
|
||
(format "expected different return type\n got ~a\n expected ~a\n"
|
||
#'τ-v #'ty_out)
|
||
#:with f- (add-orig (generate-temporary #'f) #'f)
|
||
-------------------------------------------------------
|
||
[⊢ (define/intermediate f f- res-ty e-) (⇒ : ★/t)]]
|
||
[(_ ((~datum ∀) (X:id ...)
|
||
(f [x (~optional (~datum :)) ty] ...))
|
||
e ...+) ≫
|
||
--------------------------------------------------
|
||
[≻ (define (∀ (X ...) (f [x ty] ... -> ★/t)) e ...)]])
|
||
|
||
(define-typed-syntax begin
|
||
[(_ e_unit ... e) ≫
|
||
#:do [(define-values (e-... τ... ep-effs f-effs s-effs) (walk/bind #'(e_unit ... e)))]
|
||
#:with τ (last τ...)
|
||
--------
|
||
[⊢ (begin- #,@e-...) (⇒ : τ)
|
||
(⇒ ν-ep (#,@ep-effs))
|
||
(⇒ ν-f (#,@f-effs))
|
||
(⇒ ν-s (#,@s-effs))]])
|
||
|
||
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
||
;; Sequencing & Definitions
|
||
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
||
|
||
(define-typed-syntax #%app
|
||
;; Polymorphic, Effectful Function - Perform Simple Matching on Argument Types
|
||
[(_ e_fn e_arg ...) ≫
|
||
[⊢ e_fn ≫ e_fn- (⇒ : (~∀ (X:row-id ...+) τ))]
|
||
---------------------------------------------
|
||
[≻ (call/inst e_fn- e_arg ...)]]
|
||
;; Polymorphic, Pure Function - Perform Local Inference
|
||
[(_ e_fn e_arg ...) ≫
|
||
;; compute fn type (ie ∀ and →)
|
||
[⊢ e_fn ≫ e_fn- ⇒ (~∀ Xs (~→fn tyX_in ... tyX_out))]
|
||
;; successfully matched a polymorphic fn type, don't backtrack
|
||
#:cut
|
||
#:with tyX_args #'(tyX_in ... tyX_out)
|
||
;; solve for type variables Xs
|
||
#:with [[e_arg- ...] Xs* cs] (solve #'Xs #'tyX_args this-syntax)
|
||
;; make sure types are legal
|
||
#:with tyXs (inst-types/cs #'Xs* #'cs #'Xs)
|
||
#:fail-unless (for/and ([ty (in-syntax #'tyXs)]
|
||
[x (in-syntax #'Xs)])
|
||
(instantiable? x ty))
|
||
"type variables must be flat and finite"
|
||
;; instantiate polymorphic function type
|
||
#:with [τ_in ... τ_out] (inst-types/cs #'Xs* #'cs #'tyX_args)
|
||
#:with (unsolved-X ...) (find-free-Xs #'Xs* #'τ_out)
|
||
;; arity check
|
||
#:fail-unless (stx-length=? #'[τ_in ...] #'[e_arg ...])
|
||
(num-args-fail-msg #'e_fn #'[τ_in ...] #'[e_arg ...])
|
||
;; purity check
|
||
#:fail-unless (all-pure? #'(e_fn- e_arg- ...)) "expressions must be pure"
|
||
;; compute argument types
|
||
#:with (τ_arg ...) (stx-map typeof #'(e_arg- ...))
|
||
;; typecheck args
|
||
[τ_arg τ⊑ τ_in #:for e_arg] ...
|
||
#:with τ_out* (if (stx-null? #'(unsolved-X ...))
|
||
#'τ_out
|
||
(syntax-parse #'τ_out
|
||
[(~?∀ (Y ...) τ_out)
|
||
#:fail-unless (→? #'τ_out)
|
||
(mk-app-poly-infer-error this-syntax #'(τ_in ...) #'(τ_arg ...) #'e_fn)
|
||
(for ([X (in-list (syntax->list #'(unsolved-X ...)))])
|
||
(unless (covariant-X? X #'τ_out)
|
||
(raise-syntax-error
|
||
#f
|
||
(mk-app-poly-infer-error this-syntax #'(τ_in ...) #'(τ_arg ...) #'e_fn)
|
||
this-syntax)))
|
||
(mk-∀- #'(unsolved-X ... Y ...) #'(τ_out))]))
|
||
--------
|
||
[⊢ (#%plain-app- e_fn- e_arg- ...) ⇒ τ_out*]]
|
||
;; All Other Functions
|
||
[(_ e_fn e_arg ...) ≫
|
||
[⊢ e_fn ≫ e_fn- (⇒ : (~→ τ_in ... (~Computation (~Value τ-out)
|
||
(~Endpoints τ-ep ...)
|
||
(~Roles τ-f ...)
|
||
(~Spawns τ-s ...))))]
|
||
#:fail-unless (pure? #'e_fn-) "expression not allowed to have effects"
|
||
#:fail-unless (stx-length=? #'[τ_in ...] #'[e_arg ...])
|
||
(num-args-fail-msg #'e_fn #'[τ_in ...] #'[e_arg ...])
|
||
[⊢ e_arg ≫ e_arg- (⇐ : τ_in)] ...
|
||
#:fail-unless (stx-andmap pure? #'(e_arg- ...)) "expressions not allowed to have effects"
|
||
------------------------------------------------------------------------
|
||
[⊢ (#%app- e_fn- e_arg- ...) (⇒ : τ-out)
|
||
(⇒ ν-ep (τ-ep ...))
|
||
(⇒ ν-s (τ-s ...))
|
||
(⇒ ν-f (τ-f ...))]])
|
||
|
||
(begin-for-syntax
|
||
;; find-free-Xs : (Stx-Listof Id) Type -> (Listof Id)
|
||
;; finds the free Xs in the type
|
||
(define (find-free-Xs Xs ty)
|
||
(for/list ([X (in-stx-list Xs)]
|
||
#:when (stx-contains-id? ty X))
|
||
X))
|
||
|
||
;; (SyntaxListOf ID) Type -> Bool
|
||
;; checks if the type contains any variables under unions
|
||
(define (tyvar-under-union? Xs ty)
|
||
(syntax-parse ty
|
||
[(~U* _ ...)
|
||
(for/or ([X (in-syntax Xs)])
|
||
(stx-contains-id? ty X))]
|
||
[(~Base _) #f]
|
||
[X:id #f]
|
||
[(~Any/bvs _ _ τ ...)
|
||
(for/or ([ty2 (in-syntax #'(τ ...))])
|
||
(tyvar-under-union? Xs ty2))]
|
||
[_
|
||
(type-error #:src (get-orig ty)
|
||
#:msg "tyvar-under-union?: unrecognized-type: ~a"
|
||
ty)]))
|
||
|
||
;; solve for Xs by unifying quantified fn type with the concrete types of stx's args
|
||
;; stx = the application stx = (#%app e_fn e_arg ...)
|
||
;; tyXs = input and output types from fn type
|
||
;; ie (typeof e_fn) = (-> . tyXs)
|
||
;; It infers the types of arguments from left-to-right,
|
||
;; and it expands and returns all of the arguments.
|
||
;; It returns list of 3 values if successful, else throws a type error
|
||
;; - a list of all the arguments, expanded
|
||
;; - a list of all the type variables
|
||
;; - the constraints for substituting the types
|
||
(define (solve Xs tyXs stx)
|
||
(syntax-parse tyXs
|
||
[(τ_inX ... τ_outX)
|
||
;; generate initial constraints with expected type and τ_outX
|
||
#:with (~?∀ Vs expected-ty)
|
||
(and (get-expected-type stx)
|
||
((current-type-eval) (get-expected-type stx)))
|
||
(define initial-cs
|
||
(if (and (syntax-e #'expected-ty) (stx-null? #'Vs))
|
||
(add-constraints Xs '() (list (list #'expected-ty #'τ_outX)))
|
||
'()))
|
||
(syntax-parse stx
|
||
[(_ e_fn . args)
|
||
(define-values (as- cs)
|
||
(for/fold ([as- null] [cs initial-cs])
|
||
([a (in-stx-list #'args)]
|
||
[tyXin (in-stx-list #'(τ_inX ...))])
|
||
(define ty_in (inst-type/cs/orig Xs cs tyXin datum=?))
|
||
(when (tyvar-under-union? Xs ty_in)
|
||
(type-error #:src a
|
||
#:msg (format "can't infer types with unions: ~a\nraw: ~a"
|
||
(type->str ty_in) ty_in)))
|
||
(define/with-syntax [a- ty_a]
|
||
(infer+erase (if (null? (find-free-Xs Xs ty_in))
|
||
(add-expected-type a ty_in)
|
||
a)))
|
||
(when (tyvar-under-union? Xs #'ty_a)
|
||
(type-error #:src a
|
||
#:msg (format "can't infer types with unions: ~a\nraw: ~a"
|
||
(type->str #'ty_a) #'ty_a)))
|
||
(values
|
||
(cons #'a- as-)
|
||
(add-constraints Xs cs (list (list ty_in #'ty_a))
|
||
(list (list (inst-type/cs/orig
|
||
Xs cs ty_in
|
||
datum=?)
|
||
#'ty_a))))))
|
||
|
||
(list (reverse as-) Xs cs)])]))
|
||
|
||
(define (mk-app-poly-infer-error stx expected-tys given-tys e_fn)
|
||
(format (string-append
|
||
"Could not infer instantiation of polymorphic function ~s.\n"
|
||
" expected: ~a\n"
|
||
" given: ~a")
|
||
(syntax->datum (get-orig e_fn))
|
||
(string-join (stx-map type->str expected-tys) ", ")
|
||
(string-join (stx-map type->str given-tys) ", ")))
|
||
|
||
;; covariant-Xs? : Type -> Bool
|
||
;; Takes a possibly polymorphic type, and returns true if all of the
|
||
;; type variables are in covariant positions within the type, false
|
||
;; otherwise.
|
||
(define (covariant-Xs? ty)
|
||
(syntax-parse ((current-type-eval) ty)
|
||
[(~?∀ Xs ty)
|
||
(for/and ([X (in-stx-list #'Xs)])
|
||
(covariant-X? X #'ty))]))
|
||
|
||
;; find-X-variance : Id Type [Variance] -> Variance
|
||
;; Returns the variance of X within the type ty
|
||
(define (find-X-variance X ty [ctxt-variance covariant])
|
||
(car (find-variances (list X) ty ctxt-variance)))
|
||
|
||
;; covariant-X? : Id Type -> Bool
|
||
;; Returns true if every place X appears in ty is a covariant position, false otherwise.
|
||
(define (covariant-X? X ty)
|
||
(variance-covariant? (find-X-variance X ty covariant)))
|
||
|
||
;; contravariant-X? : Id Type -> Bool
|
||
;; Returns true if every place X appears in ty is a contravariant position, false otherwise.
|
||
(define (contravariant-X? X ty)
|
||
(variance-contravariant? (find-X-variance X ty covariant)))
|
||
|
||
;; find-variances : (Listof Id) Type [Variance] -> (Listof Variance)
|
||
;; Returns the variances of each of the Xs within the type ty,
|
||
;; where it's already within a context represented by ctxt-variance.
|
||
(define (find-variances Xs ty [ctxt-variance covariant])
|
||
(syntax-parse ty
|
||
[A:id
|
||
(for/list ([X (in-list Xs)])
|
||
(cond [(free-identifier=? X #'A) ctxt-variance]
|
||
[else irrelevant]))]
|
||
[(~Any tycons)
|
||
(stx-map (λ _ irrelevant) Xs)]
|
||
[(~?∀ () (~Any tycons τ ...))
|
||
#:when (get-arg-variances #'tycons)
|
||
#:when (stx-length=? #'[τ ...] (get-arg-variances #'tycons))
|
||
(define τ-ctxt-variances
|
||
(for/list ([arg-variance (in-list (get-arg-variances #'tycons))])
|
||
(variance-compose ctxt-variance arg-variance)))
|
||
(for/fold ([acc (stx-map (λ _ irrelevant) Xs)])
|
||
([τ (in-stx-list #'[τ ...])]
|
||
[τ-ctxt-variance (in-list τ-ctxt-variances)])
|
||
(map variance-join
|
||
acc
|
||
(find-variances Xs τ τ-ctxt-variance)))]
|
||
[ty
|
||
#:when (not (for/or ([X (in-list Xs)])
|
||
(stx-contains-id? #'ty X)))
|
||
(stx-map (λ _ irrelevant) Xs)]
|
||
[_ (stx-map (λ _ invariant) Xs)])))
|