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[occurrence] subtyping, normal form, and VERY BASIC filters. Having trouble propogating variables.

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This commit is contained in:
Ben Greenman 2015-10-13 12:51:24 -04:00
parent c5d6bfbf9e
commit d7913f7753
2 changed files with 336 additions and 22 deletions
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166
tapl/stlc+occurrence.rkt
View File

@ -21,21 +21,69 @@
[(_ . x) #'(stlc+sub:#%datum . x)])
(define-type-constructor ∪ #:arity >= 1)
;; TODO disallow recursive ∪
;; -----------------------------------------------------------------------------
;; --- Union operations
;; Occurrence type operations
;; These assume that τ is a type in 'normal form'
(begin-for-syntax
;; True if τ is a union type, otherwise #f
(define (∪->list τ)
;; Ignore type constructor & the kind
;; (because there are no bound identifiers)
(syntax-parse τ
[(~∪ τ* ...)
(syntax->list #'(τ* ...))]
[_
(error '∪->list (format "Given non-ambiguous type '~a'" τ))]))
(define (list->∪ τ*)
(τ-eval #`(∪ #,@τ*)))
(define (type->filter τ)
;; Going to have the same problem here, matching on types
;; (Γ is stored insisde τ)
;; (define Π (get-context τ 'filter))
;; (Π τ))
;; TODO filter properly
#'boolean?)
(define (∖ τ1 τ2)
(cond
[(∪? τ1)
(printf "SETMINUS got an ∪ ~a\n" τ1)
(define (not-τ2? τ)
(not (typecheck? τ τ2)))
(list->∪ (filter not-τ2? (∪->list τ1)))]
[else ; do nothing
τ1]))
)
;; -----------------------------------------------------------------------------
;; --- Normal Form
(begin-for-syntax
(define τ-eval (current-type-eval))
(define (τ->symbol τ)
(cadr (syntax->datum τ)))
(define (∪-eval τ-stx)
(syntax-parse τ-stx #:datum-literals (∪)
[(∪ τ-stx* ...)
;; TODO Assumes that each τ is non-∪
;; TODO just make a set?
;; will that work if we have ∪ inside the ∪ ?
;(printf "Syntax prop type is ~a\n" (syntax-property (τ-eval τ) 'type))
(syntax-parse (τ-eval τ-stx)
[(~∪ τ-stx* ...)
;; Recursively evaluate members
(define τ**
(for/list ([τ (in-list (syntax->list #'(τ-stx* ...)))])
(let ([τ+ (∪-eval τ)])
(if (∪? τ+)
(∪->list τ+)
(list τ+)))))
;; Remove duplicates from the union, sort members
(define τ*
(sort
(remove-duplicates (syntax->list #'(τ-stx* ...)) (current-type=?))
(remove-duplicates (apply append τ**) (current-type=?))
symbol<?
#:key syntax->datum))
#:key τ->symbol)) ;; TODO handle functions & other constructors
;; Check for empty & singleton lists
(define τ
(cond
[(null? τ*)
@ -51,15 +99,107 @@
(τ-eval τ-stx)]))
(current-type-eval ∪-eval))
;; -----------------------------------------------------------------------------
;; --- Subtyping
;; Problem: matching on normal forms is tricky
;; (use stlc+reco+sub as an example)
;; - subtype U with simple, U with contained
;; - AMB : t <: (U ... t ...)
;; - SUB : a<:b => (U a t' ...) <: (U b t' ...)
;; - EXT : (U t' ...) <: (U t t' ...)
(begin-for-syntax
;; True if one ordered list (of types) is a subset of another
(define (subset? x* y* #:leq [cmp (current-typecheck-relation)])
(let loop ([x* x*] [y* y*])
(cond
[(null? x*) #t]
[(null? y*) #f]
[(cmp (car x*) (car y*))
(loop (cdr x*) (cdr y*))]
[else
(loop x* (cdr y*))])))
(define sub? (current-sub?))
(define (∪-sub? τ1-stx τ2-stx)
(define τ1 ((current-type-eval) τ1-stx))
(define τ2 ((current-type-eval) τ2-stx))
(match `(,(∪? τ1) ,(∪? τ2))
['(#f #t)
;; AMB : a<:b => a <: (U ... b ...)
(for/or ([τ (in-list (∪->list τ2))])
(sub? τ1 τ))]
['(#t #t)
(define τ1* (∪->list τ1))
(define τ2* (∪->list τ2))
(match `(,(length τ1*) ,(length τ2*))
[`(,L1 ,L2) #:when (< L1 L2)
;; - EXT : (U t' ...) <: (U t t' ...)
(subset? τ1* τ2* #:leq sub?)]
[`(,L1 ,L2) #:when (= L1 L2)
;; - SUB : a<:b => (U a t' ...) <: (U b t' ...)
;; `∪->list` guarantees same order on type members
;; `sub?` is reflexive
(andmap sub? τ1* τ2*)]
[_ #f])]
[_
;; Could be (U ...) <: T
(sub? τ1 τ2)]))
(current-sub? ∪-sub?)
(current-typecheck-relation (current-sub?))
)
;; - TEST subtyping, with 'values' and with 'functions'
;; - add filters
;; -----------------------------------------------------------------------------
;; --- Filters
(begin-for-syntax
(define (simple-Π τ)
(syntax-parse (τ-eval τ)
[~Boolean
#'boolean?]
[~Int
#'integer?]
[~Str
#'string?]
['Number
#'number?]
['Natural
#'(lambda (n) (and (integer? n) (not (negative? n))))]
[_
(error 'Π "Cannot make filter for type ~a\n" (syntax->datum τ))]))
(define current-Π (make-parameter simple-Π)))
;; - "simple", (Int ? e)
;; - "correct", where the function is effectful and independent of cond
;; - check if τ0 is a union type
;; - check if τ-filter is a subtype of τ0
;; - drop absurd branches?
;; - allow x not identifier
(define-typed-syntax test #:datum-literals (?)
[(_ [τ-filter:type ? x-stx:id] e1 e2)
;; Get the filter type, evaluate to a runtime predicate
#:with f ((current-Π) #'τ-filter)
#:fail-unless (syntax-e #'f)
(format "Could not express type '~a' as a filter." #'τ-filter-stx)
;; TypeCheck e0:normally, e1:positive, e2:negative
#:with (x τ0) (infer+erase #'x-stx)
;; #:when (printf "Check'd e0, type is ~a\n" (syntax->datum #'τ0))
#:with [_ e1+ τ1] (infer/tyctx+erase #'([x-stx : τ-filter]) #'e1)
;; #:when (printf "Check'd e1\n")
#:with [_ e2+ τ2] (infer/tyctx+erase #`([x-stx : #,(∖ #'τ0 #'τ-filter)]) #'e2)
;; #:when (printf "Checked e2\n")
;; Expand to a conditional, using the runtime predicate
(⊢ (if (f x) e1+ e2+)
: (∪ τ1 τ2))])
;; - add filters (install filters, at start of file)
;; - TEST basic filters
;; - TEST function filters (delayed filters?)
;; - disallow (U (-> ...) (-> ...))
;; - TEST latent filters -- listof BLAH
;; - integrate with sysf
;; (begin-for-syntax
;; (define stlc:sub? (current-sub?))
;; )

192
tapl/tests/stlc+occurrence-tests.rkt
View File

@ -16,7 +16,7 @@
#:with-msg "Improper usage of type constructor ∪: ∪, expected >= 1 arguments")
(typecheck-fail
(λ ([x : (∪)]) x)
#:with-msg "empty union type")
#:with-msg "Improper usage of type constructor ∪")
(typecheck-fail
(λ ([x : (∪ ∪)]) x)
#:with-msg "Improper usage of type constructor ∪")
@ -45,14 +45,188 @@
: (→ (∪ Boolean Int) Int))
(check-type (λ ([x : (∪ Int Boolean Boolean Int)]) x)
: (→ (∪ Boolean Int) (∪ Boolean Int)))
(check-type (λ ([x : (∪ (∪ Int Boolean))]) 42)
: (→ (∪ Int Boolean) Int))
(check-type (λ ([x : (∪ Int Boolean)]) 42)
: (→ (∪ (∪ Int Boolean)) Int))
(check-type (λ ([x : (∪ Int Boolean)]) 42)
: (→ (∪ (∪ Int Boolean) (∪ Int Boolean)) Int))
;; -----------------------------------------------------------------------------
;; --- basic subtyping
;; (check-type 1 : (∪ Int))
;; (check-type 1 : (∪ Int Boolean))
;; (check-type 1 : (∪ Boolean Int))
;; (check-type 1 : (∪ Boolean Int (→ Boolean Boolean)))
;; (check-type 1 : (∪ (∪ Int)))
;; --- subtyping
;; (check-not-type 1 : (∪ Boolean))
;; (check-not-type 1 : (∪ Boolean (→ Int Int)))
;; ---- basics
(check-type 1 : (∪ Int))
(check-type 1 : (∪ (∪ Int)))
(check-not-type 1 : (∪ Boolean))
;; - AMB : t <: t' => t <: (U ... t' ...)
(check-type 1 : (∪ Boolean Int))
(check-type -1 : (∪ Int Boolean))
(check-type 1 : (∪ Boolean Int (→ Boolean Boolean)))
(check-type 1 : (∪ (∪ Int Boolean) (∪ Int Boolean)))
(check-not-type 1 : (∪ Boolean (→ Int Int)))
;; --- EXT : (U t' ...) <: (U t t' ...)
(check-type (λ ([x : (∪ Int Boolean)]) x)
: (→ (∪ Int Boolean) (∪ Int Boolean Str)))
(check-type (λ ([x : (∪ Int Boolean)]) x)
: (→ (∪ Boolean) (∪ Int Boolean Str)))
(check-not-type (λ ([x : (∪ Int Boolean)]) x)
: (→ (∪ Int Boolean) (∪ Int)))
(check-not-type (λ ([x : (∪ Int Boolean)]) x)
: (→ (∪ Boolean Int Str) (∪ Int Boolean)))
;; --- SUB : a<:b => (U a t' ...) <: (U b t' ...)
(check-type (λ ([x : (∪ Int Str)]) x)
: (→ (∪ Int Str) (∪ Num Str)))
(check-type (λ ([x : (∪ Int Str)]) x)
: (→ (∪ Nat Str) (∪ Num Str)))
(check-type (λ ([x : (∪ Int Str)]) x)
: (→ (∪ Int Str) Top))
(check-not-type (λ ([x : (∪ Int Str)]) x)
: (→ Top (∪ Num Str)))
;; -----------------------------------------------------------------------------
;; --- Basic Filters (applying functions)
;; --- is-boolean?
(check-type
(λ ([x : (∪ Boolean Int)])
(test [Boolean ? x]
#t
#f))
: (→ (∪ Boolean Int) Boolean))
(check-type-and-result
((λ ([x : (∪ Boolean Int)])
(test (Boolean ? x)
#t
#f)) #t)
: Boolean ⇒ #t)
(check-type-and-result
((λ ([x : (∪ Boolean Int)])
(test (Boolean ? x)
#t
#f)) 902)
: Boolean ⇒ #f)
;; --- successor
;; (check-type
;; (λ ([x : (∪ Int Boolean)])
;; (test (Int ? x)
;; (+ 1 x)
;; (if x 1 0)))
;; : Int)
;; (check-type-and-result
;; ((λ ([x : (∪ Int Boolean)])
;; (test (Int ? x)
;; (+ 1 x)
;; (if x 1 0))) #f)
;; : Int ⇒ 0)
;; (check-type-and-result
;; ((λ ([x : (∪ Int Boolean)])
;; (test (Int ? x)
;; (+ 1 x)
;; (if x 1 0))) #t)
;; : Int ⇒ 1)
;; (check-type-and-result
;; ((λ ([x : (∪ Int Boolean)])
;; (test (Int ? x)
;; (+ 1 x)
;; (if x 1 0))) 9000)
;; : Int ⇒ 9001)
;; ;; --- Do-nothing filter
(check-type
(λ ([x : Int])
(test (Int ? x) #t #f))
: (→ Int Boolean))
(check-type
(λ ([x : Int])
(test (Boolean ? x) 1 0))
: (→ Int Int))
;; --- Filter a subtype
;; (check-type
;; (λ ([x : (∪ Nat Boolean)])
;; (test (Int ? x)
;; x
;; x))
;; : (→ (∪ Nat Bool) (∪ Int (∪ Nat Bool))))
;; (check-type
;; (λ ([x : (∪ Int Bool)])
;; (test (Nat ? x)
;; (+ 2 x)
;; x))
;; : (→ (∪ Bool Int) (∪ Int Bool)))
;; (check-type-and-result
;; ((λ ([x : (∪ Int Bool)])
;; (test (Num ? x)
;; #f
;; x)) #t)
;; : (→ (∪ Int Bool) Bool)
;; ⇒ #t)
;; ;; Should filter all the impossible types
;; (check-type-and-result
;; ((λ ([x : (∪ Nat Int Num Bool)])
;; (test (Num ? x)
;; #f
;; x)) #t)
;; : (→ (∪ Nat Int Num Bool) Bool)
;; ⇒ #t)
;; -----------------------------------------------------------------------------
;; --- misc subtyping + filters (regression tests)
(check-type
(λ ([x : (∪ Int Boolean)])
(test (Int ? x)
0
1))
: (→ (∪ Int Boolean) Nat))
(check-type
(λ ([x : (∪ Int Boolean)])
(test (Int ? x)
0
1))
: (→ (∪ Int Boolean) Int))
;; -----------------------------------------------------------------------------
;; --- Invalid filters
(typecheck-fail
(λ ([x : (∪ Int Boolean)])
(test (1 ? x) #t #f))
#:with-msg "not a valid type")
(typecheck-fail
(test (1 ? 1) #t #f)
#:with-msg "not a valid type")
(typecheck-fail
(test (1 ? 1) #t #f)
#:with-msg "not a valid type")
(typecheck-fail
(test (#f ? #t) #t #f)
#:with-msg "not a valid type")
;; -----------------------------------------------------------------------------
;; --- TODO Subtypes should not be collapsed
;; (Not sure how to test this, because type=? is subtyping and these ARE subtypes)
;; (check-not-type (λ ([x : (∪ Int Nat)]) #t)
;; : (→ Nat Boolean))
;; (check-not-type (λ ([x : (∪ Int Nat)]) #t)
;; : (→ Int Boolean))
;; ;; -----------------------------------------------------------------------------
;; ;; --- Filter values (should do nothing)
;; (check-type
;; (test (Int ? 1) #t #f)
;; : Boolean)