258 lines
9.4 KiB
Racket
258 lines
9.4 KiB
Racket
#lang turnstile
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(provide for/fold
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for
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for/list
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for/set
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for/sum
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for/first)
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(require "core-types.rkt")
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(require "sequence.rkt")
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(require (only-in "list.rkt" List ~List))
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(require (only-in "set.rkt" Set ~Set))
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(require (only-in "hash.rkt" Hash ~Hash))
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(require (only-in "prim.rkt" Bool + #%datum))
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(require (only-in "core-expressions.rkt" let unit tuple-select mk-tuple))
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(require "maybe.rkt")
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(require (postfix-in - (only-in racket/set
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for/set
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in-set)))
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(begin-for-syntax
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(define-splicing-syntax-class iter-clause
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#:attributes (parend)
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#:datum-literals (:)
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(pattern [x:id seq:expr]
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#:attr parend #'[x seq])
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(pattern [x:id : τ:type seq:expr]
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#:attr parend #'[x : τ seq])
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(pattern [(k:id v:id) hash-seq:expr]
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#:attr parend #'[(k v) hash-seq])
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(pattern (~seq #:when pred:expr)
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#:attr parend #'(#:when pred))
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(pattern (~seq #:unless pred:expr)
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#:attr parend #'(#:unless pred))
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(pattern (~seq #:break pred:expr)
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#:attr parend #'(#:break pred))))
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;; a Binding is a (SyntaxList Id Id Type), i.e. #'(x x- τ-x)
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(begin-for-syntax
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(struct loop-clause (exp bindings) #:transparent)
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(struct directive (kw exp) #:transparent))
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;; (SyntaxListOf LoopClause) -> (Syntax LoopClause- (Binding ...))
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(define-for-syntax (analyze-for-clauses clauses)
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(define-values (br binds)
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(for/fold ([body-rev '()]
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[bindings '()])
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([clause (in-syntax clauses)])
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(match (analyze-for-clause clause bindings)
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[(loop-clause exp bs)
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(values (cons exp body-rev)
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(append bindings bs))]
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[(directive kw exp)
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(values (list* exp kw body-rev)
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bindings)])))
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#`(#,(reverse br)
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#,binds))
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;; iter-clause (Listof Binding) -> (U iter-clause directive)
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(define-for-syntax (analyze-for-clause clause ctx)
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(define/with-syntax ([y y- τ-y] ...) ctx)
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(syntax-parse clause
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#:datum-literals (:)
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[[x:id seq:expr]
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#:and (~typecheck
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[[y ≫ y-- : τ-y] ... ⊢ seq ≫ seq- (⇒ : τ-seq)])
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#:fail-unless (pure? #'seq-) "pure"
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#:with x- (generate-temporary #'x)
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#:do [(define-values (seq-- τ-elems) (make-sequence #'seq- #'τ-seq))]
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(loop-clause (substs #'(y- ...) #'(y-- ...)
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#`[x- #,seq--]
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free-identifier=?)
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(list #`(x x- #,τ-elems)))]
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[[x:id : τ:type seq:expr]
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#:with seq+ (add-expected-type #'seq #'τ.norm)
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#:do [(match-define (list seq- (list (list x- τ-elems)))
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(analyze-for-clause (syntax/loc clause [x seq+])))]
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#:fail-unless (<: τ-elems #'τ.norm) "unexpected type"
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(loop-clause #`[#,x- #,seq-]
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(list #`(x #,x- τ.norm)))]
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[[(k:id v:id) hash-seq:expr]
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#:and (~typecheck
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[[y ≫ y-- : τ-y] ... ⊢ hash-seq ≫ hash-seq- (⇒ : (~Hash K V))])
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#:fail-unless (pure? #'hash-seq-) "pure"
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#:with (k- v-) (generate-temporaries #'(k v))
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(loop-clause (substs #'(y- ...) #'(y-- ...)
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#`[(k- v-) (in-hash- hash-seq-)]
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free-identifier=?)
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(list #'(k k- K) #'(v v- V)))]
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[(dir:keyword pred)
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#:and (~typecheck
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[[y ≫ y-- : τ-y] ... ⊢ pred ≫ pred- (⇐ : Bool)])
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#:fail-unless (pure? #'pred-) "pure"
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(directive #'dir (substs #'(y- ...) #'(y-- ...)
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#'pred-
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free-identifier=?))]))
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;; Expression Type -> (Values Expression Type)
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;; Determine what kind of sequence we're dealing with;
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;; if it's not already in Sequence form, wrap the expression in the appropriate in-* form
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;; also figure out what the type of elements are to associate with the loop variable
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;; hashes handled separately
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(define-for-syntax (make-sequence e τ)
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(syntax-parse τ
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[(~Sequence t)
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(values e #'t)]
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[(~List t)
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(values #`(in-list- #,e) #'t)]
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[(~Set t)
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(values #`(in-set- #,e) #'t)]
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[_
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(type-error #:src e
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#:msg "not an iterable type: ~a" τ)]))
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(define-for-syntax (bind-renames renames body)
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(syntax-parse renames
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[([x:id x-:id] ...)
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#:with (x-- ...) (map syntax-local-identifier-as-binding (syntax->list #'(x- ...)))
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(quasisyntax/loc body
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(let- ()
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(define-syntax x (make-variable-like-transformer #'x--)) ...
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#,body))]))
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(define-typed-syntax for/fold
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[(for/fold ([acc:id (~optional (~datum :)) τ-acc init] ...+)
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(clause:iter-clause
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...)
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e-body ...+) ≫
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[⊢ init ≫ init- (⇐ : τ-acc)] ...
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#:fail-unless (all-pure? #'(init- ...)) "expression must be pure"
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#:with (clauses- ([x x- τ] ...)) (analyze-for-clauses #'(clause.parend ...))
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#:do [(define num-accs (length (syntax->list #'(τ-acc ...))))]
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#:with body-ty (if (= 1 num-accs)
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(first (syntax->list #'(τ-acc ...)))
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(type-eval #'(Tuple (~@ τ-acc ...))))
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[[[x ≫ x-- : τ] ...]
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[[acc ≫ acc- : τ-acc] ...] ⊢ (block e-body ...) ≫ e-body-
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(⇐ : body-ty)
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(⇒ ν-ep (~effs τ-ep ...))
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(⇒ ν-s (~effs τ-s ...))
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(⇒ ν-f (~effs τ-f ...))]
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-------------------------------------------------------
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[⊢ (values->tuple #,num-accs
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(for/fold- ([acc- init-] ...)
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clauses-
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#,(bind-renames #'([x-- x-] ...) #`(tuple->values #,num-accs e-body-))))
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(⇒ : body-ty)
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(⇒ ν-ep (τ-ep ...))
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(⇒ ν-s (τ-s ...))
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(⇒ ν-f (τ-f ...))]]
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[(for/fold (accs ... [acc:id init] more-accs ...)
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clauses
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e-body ...+) ≫
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[⊢ init ≫ _ (⇒ : τ-acc)]
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---------------------------------------------------
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[≻ (for/fold (accs ... [acc τ-acc init] more-accs ...)
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clauses
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e-body ...)]])
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(define-syntax-parser tuple->values
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[(_ n:nat e:expr)
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(define arity (syntax-e #'n))
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(cond
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[(= 1 arity)
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#'e]
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[else
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(define/with-syntax tmp (generate-temporary 'tup))
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(define projections
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(for/list ([i (in-range arity)])
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#`(#%app- tuple-select #,i tmp)))
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#`(let- ([tmp e])
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(#%app- values- #,@projections))])])
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#;(tuple->values 1 (tuple 0))
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(define-syntax-parser values->tuple
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[(_ n:nat e:expr)
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(define arity (syntax-e #'n))
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(cond
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[(= 1 arity)
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#'e]
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[else
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(define/with-syntax (tmp ...) (generate-temporaries (make-list arity 'values->tuple)))
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#`(let-values- ([(tmp ...) e])
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(#%app- mk-tuple (#%app- list- tmp ...)))])])
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(define-typed-syntax (for/list (clause:iter-clause ...)
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e-body ...+) ≫
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#:with (clauses- ([x x- τ] ...)) (analyze-for-clauses #'(clause.parend ...))
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[[x ≫ x-- : τ] ... ⊢ (block e-body ...) ≫ e-body-
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(⇒ : τ-body)
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(⇒ ν-ep (~effs τ-ep ...))
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(⇒ ν-s (~effs τ-s ...))
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(⇒ ν-f (~effs τ-f ...))]
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----------------------------------------------------------------------
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[⊢ (for/list- clauses-
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#,(bind-renames #'([x-- x-] ...) #'e-body-))
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(⇒ : (List τ-body))
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(⇒ ν-ep (τ-ep ...))
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(⇒ ν-s (τ-s ...))
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(⇒ ν-f (τ-f ...))])
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(define-typed-syntax (for/set (clause:iter-clause ...)
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e-body ...+) ≫
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#:with (clauses- ([x x- τ] ...)) (analyze-for-clauses #'(clause.parend ...))
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[[x ≫ x-- : τ] ... ⊢ (block e-body ...) ≫ e-body-
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(⇒ : τ-body)
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(⇒ ν-ep (~effs τ-ep ...))
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(⇒ ν-s (~effs τ-s ...))
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(⇒ ν-f (~effs τ-f ...))]
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----------------------------------------------------------------------
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[⊢ (for/set- clauses-
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#,(bind-renames #'([x-- x-] ...) #'e-body-))
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(⇒ : (Set τ-body))
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(⇒ ν-ep (τ-ep ...))
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(⇒ ν-s (τ-s ...))
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(⇒ ν-f (τ-f ...))])
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(define-typed-syntax (for/sum (clause ...)
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e-body ...+) ≫
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----------------------------------------------------------------------
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[≻ (for/fold ([acc 0])
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(clause ...)
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(+ acc (let () e-body ...)))])
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(define-typed-syntax (for (clause ...)
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e-body ...+) ≫
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----------------------------------------------------------------------
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[≻ (for/fold ([acc unit])
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(clause ...)
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e-body ...
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acc)])
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(define-typed-syntax (for/first (clause:iter-clause ...)
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e-body ...+) ≫
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#:with (clauses- ([x x- τ] ...)) (analyze-for-clauses #'(clause.parend ...))
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[[x ≫ x-- : τ] ... ⊢ (block e-body ...) ≫ e-body-
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(⇒ : τ-body)
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(⇒ ν-ep (~effs τ-ep ...))
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(⇒ ν-s (~effs τ-s ...))
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(⇒ ν-f (~effs τ-f ...))]
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[[res ≫ _ : τ-body] ⊢ res ≫ res- (⇒ : _)]
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----------------------------------------------------------------------
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[⊢ (let- ()
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(define- res-
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(for/first- clauses-
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#,(bind-renames #'([x-- x-] ...) #'e-body-)))
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(if- res-
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(some res-)
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none))
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(⇒ : (Maybe τ-body))
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(⇒ ν-ep (τ-ep ...))
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(⇒ ν-s (τ-s ...))
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(⇒ ν-f (τ-f ...))])
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