364 lines
15 KiB
Racket
364 lines
15 KiB
Racket
#lang racket/base
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(require
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racket/match
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(for-syntax racket/base syntax/parse syntax/parse/experimental/template
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racket/set syntax/stx racket/syntax
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"stx-utils.rkt")
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(for-meta 2 racket/base syntax/parse)
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"typecheck.rkt")
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(require (except-in "stlc.rkt" #%app #%datum λ #%module-begin +))
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(require (prefix-in stlc: "stlc.rkt"))
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(provide (all-from-out "stlc.rkt"))
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(provide
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define-type cases
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(rename-out
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[datum/tc #%datum]
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#;[void/tc void] [printf/tc printf]
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[λ/tc λ] [let/tc let]
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; for #%app, must prefix and re-provide because this file needs to use racket's #%app
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[stlc:#%app #%app]
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; [app/tc #%app]
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[define/tc define]
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[begin/tc begin]
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[if/tc if]
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[datum/tc #%datum] [module-begin/tc #%module-begin]
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[cons/tc cons] [null/tc null] [null?/tc null?] [first/tc first] [rest/tc rest] [list/tc list]))
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;; Simply-Typed Lambda Calculus+
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;; - stlc extended with practical language feature
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;; - implemented in racket
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;; Features:
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;; - stlc
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;; - multi-expr lam bodies
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;; - printing
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;; - cons + listops
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;; - more prim types (bool, string)
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;; - more prim ops
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;; - user (recursive) function definitions
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;; - user (recursive) (variant) type-definitions + cases
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;; - var args: TODO: primops can handle multiple args but not general application
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(define-and-provide-builtin-types String Bool Listof Unit)
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(provide (for-syntax assert-Unit-type assert-String-type))
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(define-for-syntax (assert-Unit-type e) (assert-type e #'Unit))
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(define-for-syntax (assert-String-type e) (assert-type e #'String))
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;; define-type ----------------------------------------------------------------
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(define-syntax (define-type stx)
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(syntax-parse stx #:datum-literals (variant)
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[(_ τ:id (variant (Cons:id τ_fld ...) ...))
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#:with ((x ...) ...) (stx-map generate-temporaries #'((τ_fld ...) ...))
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#:when (Γ (type-env-extend #'([Cons (τ_fld ... → τ)] ...)))
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#'(begin
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(struct Cons (x ...) #:transparent) ...)]
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[(_ τ:id (Cons:id τ_fld ...))
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#:with (x ...) (generate-temporaries #'(τ_fld ...))
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#:when (Γ (type-env-extend #'([Cons (τ_fld ... → τ)])))
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#'(begin
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(struct Cons (x ...) #:transparent))]))
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(define-syntax (cases stx)
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(syntax-parse stx #:literals (→)
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[(_ e [Cons (x ...) body ... body_result] ...)
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#:with e+ (expand/df #'e)
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#:with (Cons+ ...) (stx-map expand/df #'(Cons ...))
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#:with ((τ ... → τ_Cons) ...) (stx-map typeof #'(Cons+ ...))
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#:when (stx-andmap (λ (τ) (assert-type #'e+ τ)) #'(τ_Cons ...))
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#:with ((lam (x+ ...) body+ ... body_result+) ...)
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(stx-map (λ (bods xs τs)
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(with-extended-type-env
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(stx-map list xs τs)
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(expand/df #`(λ #,xs #,@bods))))
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#'((body ... body_result) ...)
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#'((x ...) ...)
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#'((τ ...) ...))
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#:when (stx-andmap (λ (bods) (stx-andmap assert-Unit-type bods)) #'((body+ ...) ...))
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#:with (τ_result ...) (stx-map typeof #'(body_result+ ...))
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#:when (or (null? (syntax->list #'(τ_result ...)))
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(andmap (λ (τ) (type=? τ (car (syntax->list #'(τ_result ...)))))
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(cdr (syntax->list #'(τ_result ...)))))
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(⊢ (syntax/loc stx (match e+ [(Cons+ x+ ...) body+ ... body_result+] ...))
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(car (syntax->list #'(τ_result ...))))]))
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;; typed forms ----------------------------------------------------------------
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(define-syntax (datum/tc stx)
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(syntax-parse stx
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[(_ . s:str) (⊢ (syntax/loc stx (#%datum . s)) #'String)]
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[(_ . b:boolean) (⊢ (syntax/loc stx (#%datum . b)) #'Bool)]
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[(_ . x) #'(stlc:#%datum . x)]))
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(define-syntax (begin/tc stx)
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(syntax-parse stx
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[(_ e ... e_result)
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#:with (e+ ... e_result+) (stx-map expand/df #'(e ... e_result))
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#:when (stx-andmap assert-Unit-type #'(e+ ...))
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(⊢ (syntax/loc stx (begin e+ ... e_result+)) (typeof #'e_result+))]))
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#;(define-syntax (void/tc stx)
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(syntax-parse stx
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[(_) (⊢ (syntax/loc stx (void)) #'Unit)]))
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(define-syntax (printf/tc stx)
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(syntax-parse stx
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[(_ τs str . args)
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#:when (curly-parens? #'τs)
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#:with str+ (expand/df #'str)
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#:when (assert-String-type #'str+)
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#:with args+ (stx-map expand/df #'args)
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#:when (stx-andmap assert-type #'args+ #'τs)
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(⊢ (syntax/loc stx (printf str+ . args+)) #'Unit)]
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[(_ str . args)
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#:fail-unless (null? (syntax->list #'args)) "Please provide type annotations for arguments"
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#:with str+ (expand/df #'str)
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#:when (assert-String-type #'str+)
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(⊢ (syntax/loc stx (printf str+)) #'Unit)]))
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(define-primop + : (Int ... → Int))
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(define-primop - : (Int Int ... → Int))
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(define-primop = : (Int Int Int ... → Bool))
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(define-primop < : (Int Int Int ... → Bool))
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(define-primop or : (Bool ... → Bool))
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(define-primop and : (Bool ... → Bool))
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(define-primop not : (Bool → Bool))
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(define-primop abs : (Int → Int))
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(define-primop void : (→ Unit))
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(define-syntax (λ/tc stx)
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(syntax-parse stx #:datum-literals (:)
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[(_ ([x:id : τ] ...) e ... e_result)
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;; the with-extended-type-env must be outside the expand/df (instead of
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;; around just the body) bc ow the parameter will get restored to the old
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;; value before the local-expand happens
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#:with (lam xs . es+) (with-extended-type-env #'([x τ] ...)
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(expand/df #'(λ (x ...) e ... e_result)))
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;; manually handle identifiers here
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;; - since Racket has no #%var hook, ids didn't get "expanded" in the previous line
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;; and thus didn't get a type
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;; TODO: can I put this somewhere else where it's more elegant?
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#:with (e++ ... e_result++) (with-extended-type-env #'([x τ] ...)
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(stx-map (λ (e) (if (identifier? e) (expand/df e) e)) #'es+))
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;; manually handle the implicit begin
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#:when (stx-map assert-Unit-type #'(e++ ...))
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#:with τ_body (typeof #'e_result++)
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(⊢ (syntax/loc stx (lam xs e++ ... e_result++)) #'(τ ... → τ_body))]))
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;; #%app
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#;(define-syntax (app/tc stx)
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(syntax-parse stx #:literals (→)
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[(_ e_fn e_arg ...)
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#:with (e_fn+ e_arg+ ...) (stx-map expand/df #'(e_fn e_arg ...))
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#:with (τ ... → τ_res) (typeof #'e_fn+)
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#:when (stx-andmap assert-type #'(e_arg+ ...) #'(τ ...))
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(⊢ (syntax/loc stx (#%app e_fn+ e_arg+ ...)) #'τ_res)]
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[(_ e ...) #'(stlc:#%app e ...)]))
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(define-syntax (let/tc stx)
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(syntax-parse stx #:datum-literals (:)
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[(_ ([x:id e_x] ...) e ... e_result)
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#:with (e_x+ ...) (stx-map expand/df #'(e_x ...))
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#:with (τ ...) (stx-map typeof #'(e_x+ ...))
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#:with (lam (x+ ...) e+ ... e_result+)
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(with-extended-type-env #'([x τ] ...)
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(expand/df #'(λ (x ...) e ... e_result)))
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#:when (stx-andmap assert-Unit-type #'(e+ ...))
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(⊢ (syntax/loc stx (let ([x+ e_x+] ...) e+ ... e_result+)) (typeof #'e_result+))]))
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(define-syntax (if/tc stx)
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(syntax-parse stx
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[(_ e_test e1 e2)
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#:with e_test+ (expand/df #'e_test)
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#:when (assert-type #'e_test+ #'Bool)
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#:with e1+ (expand/df #'e1)
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#:with e2+ (expand/df #'e2)
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#:when (or (type=? (typeof #'e1+) (typeof #'e2+))
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(type-error #:src stx
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#:msg "IF branches have differing types: branch ~a has type ~a and branch ~a has type ~a"
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#'e1 (typeof #'e1+)
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#'e2 (typeof #'e2+)))
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(⊢ (syntax/loc stx (if e_test+ e1+ e2+)) (typeof #'e1+))]))
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;; lists ----------------------------------------------------------------------
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(define-syntax (cons/tc stx)
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(syntax-parse stx
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[(_ {T} e1 e2)
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#:with e1+ (expand/df #'e1)
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#:with e2+ (expand/df #'e2)
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#:when (assert-type #'e1+ #'T)
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#:when (assert-type #'e2+ #'(Listof T))
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(⊢ (syntax/loc stx (cons e1+ e2+)) #'(Listof T))]))
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(define-syntax (null/tc stx)
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(syntax-parse stx
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[(_ {T}) (⊢ (syntax/loc stx null) #'(Listof T))]))
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(define-syntax (list/tc stx)
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(syntax-parse stx
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[(_ {τ}) #'(null/tc {τ})]
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[(_ {τ} x . rst) #'(cons/tc {τ} x (list/tc {τ} . rst))]))
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(define-syntax (null?/tc stx)
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(syntax-parse stx
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[(_ {T} e)
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#:with e+ (expand/df #'e)
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#:when (assert-type #'e+ #'(Listof T))
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(⊢ (syntax/loc stx (null? e+)) #'Bool)]))
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(define-syntax (first/tc stx)
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(syntax-parse stx
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[(_ {T} e)
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#:with e+ (expand/df #'e)
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#:when (assert-type #'e+ #'(Listof T))
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(⊢ (syntax/loc stx (car e+)) #'T)]))
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(define-syntax (rest/tc stx)
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(syntax-parse stx
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[(_ {T} e)
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#:with e+ (expand/df #'e)
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#:when (assert-type #'e+ #'(Listof T))
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(⊢ (syntax/loc stx (cdr e+)) #'(Listof T))]))
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;; define, module-begin -------------------------------------------------------
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(define-syntax (define/tc stx)
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(syntax-parse stx #:datum-literals (:)
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[(_ (f:id [x:id : τ] ...) : τ_result e ...)
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#:when (Γ (type-env-extend #'([f (τ ... → τ_result)])))
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;; If I use the (commented-out) copied-from-λ impl below,
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;; get "f unbound identifier error" for example:
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;; (define (g [y : Int]) : Int
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;; (+ (f y) 1))
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;; (define (f [x : Int]) : Int
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;; (+ x 1))
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;; But if I define define/tc interms of λ/tc, the example works.
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;; I'm guessing it's because the call to expand/df is deferred
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;; in the latter case to until after the racket internal def code first
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;; does its peek-expand to get all the λ/tcs, and thus all the f's have
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;; been added to the internal def ctxt
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; #:with (lam xs . es+) (with-extended-type-env #'([x τ] ...)
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; (expand/df #'(λ (f x ...) e ... e_result)))
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; #:with (e++ ... e_result++) (with-extended-type-env #'([x τ] ...)
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; (stx-map (λ (e) (if (identifier? e) (expand/df e) e)) #'es+))
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; #:when (stx-map assert-Unit-type #'(e++ ...))
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; #:with τ_body (typeof #'e_result++)
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; (⊢ (syntax/loc stx (define xs+ e++ ... e_result++)) #'(τ ... → τ_body))]
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#'(define f (λ/tc ([x : τ] ...) e ...))]
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[(_ x:id e) #'(define x e)]))
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(begin-for-syntax
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;; EXTENSIBILITY NOTE:
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;; Originally, define-type was a #:literal instead of a #:datum-literal, but
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;; this became a problem when sysf extended define-type (but not modul-begin).
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;; Putting define-type in the #:literals list makes it always expect the stlc
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;; version of define-type, so it wasnt getting properly parsed in sysf.
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;;
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;; Similarly, I had to define the define-type pattern below to avoid explicitly
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;; mentioning define-type on the rhs, otherwise it would again lock in the stlc
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;; version of define-type.
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(define-syntax-class maybe-def #:datum-literals (define variant define-type)
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(pattern define-fn
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#:with (define (f x ...) body ...) #'define-fn
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#:attr fndef #'(define-fn)
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#:attr e #'() #:attr tydecl #'())
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(pattern define-variant-type-decl
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#:with (define-type TypeName (variant (Cons fieldτ ...) ...))
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#'define-variant-type-decl
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#:attr tydecl #'(define-variant-type-decl)
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#:attr fndef #'() #:attr e #'())
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(pattern define-type-decl
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#:with (define-type TypeName:id (Cons:id fieldτ ...) ...)
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#'define-type-decl
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#:attr tydecl #'(define-type-decl)
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#:attr fndef #'() #:attr e #'())
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(pattern exp:expr
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#:attr tydecl #'() #:attr fndef #'()
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#:attr e #'(exp)))
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(define-syntax-class strct #:literals (begin define-values define-syntaxes)
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(pattern
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(begin
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(define-values (x ...) mk-strct-type-def)
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(define-syntaxes (y) strct-info-def))
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#:attr def-val #'(define-values (x ...) mk-strct-type-def)
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#:attr def-syn #'(define-syntaxes (y) strct-info-def)))
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(define-syntax-class def-val #:literals (define-values)
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(pattern (define-values (x ...) vals)
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#:attr lhs #'(x ...)
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#:attr rhs #'vals))
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(define-syntax-class def-syn #:literals (define-syntaxes)
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(pattern (define-syntaxes (x) stxs)
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#:attr lhs #'x
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#:attr rhs #'stxs))
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)
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(define-syntax (module-begin/tc stx)
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(syntax-parse stx #:literals (begin)
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[(_ mb-form:maybe-def ...)
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;; handle define-type
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#:with (deftype ...) (template ((?@ . mb-form.tydecl) ...))
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; #:with ((begin deftype+ ...) ...) (stx-map expand/df/module-ctx #'(deftype ...))
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; #:with (structdef ...) (stx-flatten #'((deftype+ ...) ...))
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; #:with (structdef+:strct ...) (stx-map expand/df/module-ctx #'(structdef ...))
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; #:with (def-val:def-val ...) #'(structdef+.def-val ...)
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; #:with (def-val-lhs ...) #'(def-val.lhs ...)
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; #:with (def-val-rhs ...) #'(def-val.rhs ...)
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; #:with (def-syn:def-syn ...) #'(structdef+.def-syn ...)
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; #:with (def-syn-lhs ...) #'(def-syn.lhs ...)
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; #:with (def-syn-rhs ...) #'(def-syn.rhs ...)
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;; handle defines
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#:with (deffn ...) (template ((?@ . mb-form.fndef) ...))
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; #:with (deffn+:def-val ...) (stx-map expand/df/module-ctx #'(deffn ...))
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; #:with (f ...) #'(deffn+.lhs ...)
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; #:with (v ...) #'(deffn+.rhs ...)
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#:with (e ...) (template ((?@ . mb-form.e) ...))
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;; base type env
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; #:when (Γ (type-env-extend #'((+ (Int Int → Int)))))
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;; NOTE: for struct def, define-values *must* come before define-syntaxes
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;; ow, error, eg: "Just10: unbound identifier; also, no #%top syntax transformer is bound"
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(quasisyntax/loc stx
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(#%module-begin
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#,(expand/df #'(let ()
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deftype ...
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;structdef ...
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deffn ...
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e ...
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(void)))
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; #,(expand/df #'(let-values ([def-val-lhs def-val-rhs] ...)
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; (let-syntax ([def-syn-lhs def-syn-rhs] ...)
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; (letrec-values ([f v] ...) e ... (void)))))
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(define #,(datum->syntax stx 'runtime-env)
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(for/hash ([x:τ '#,(map (λ (xτ) (cons (car xτ) (syntax->datum (cdr xτ))))
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(hash->list (Γ)))])
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(values (car x:τ) (cdr x:τ))))
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))]))
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;; type checking testing: -----------------------------------------------------
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(require rackunit)
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(require (for-syntax rackunit "typecheck.rkt"))
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(provide check-equal?)
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(provide check-type-error check-type check-type-and-result check-not-type)
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(define-syntax (check-type-error stx)
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(syntax-parse stx
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[(_ e)
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#:when (check-exn exn:fail? (λ () (expand/df #'e)))
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#'(void)]))
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(define-syntax (check-type stx)
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(syntax-parse stx #:datum-literals (:)
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[(_ e : τ)
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#:with e+ (expand/df #'e)
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#:when (check-true (assert-type #'e+ #'τ)
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(format "Expected type ~a but got type ~a" #'τ (typeof #'e)))
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#'(void)]))
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(define-syntax (check-not-type stx)
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(syntax-parse stx #:datum-literals (:)
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[(_ e : τ)
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#:with e+ (expand/df #'e)
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#:when (check-false (type=? (typeof #'e+) #'τ)
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(format "Expected type to not be ~a but got type ~a" #'τ (typeof #'e)))
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#'(void)]))
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(define-syntax (check-type-and-result stx)
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(syntax-parse stx #:datum-literals (: =>)
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[(_ e : τ => v)
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#'(begin (check-type e : τ)
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(check-equal? e v))]))
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