Improve scoping structure of for-clauses
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4b692428af
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@ -26,17 +26,19 @@
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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)
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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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@ -46,34 +48,44 @@
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#`(#,(reverse br)
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#,binds))
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;; iter-clause -> (U iter-clause directive)
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(define-for-syntax (analyze-for-clause clause)
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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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[⊢ seq ≫ seq- (⇒ : τ-seq)])
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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 #`[x #,seq--]
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(list #`(x #,τ-elems)))]
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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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#:do [(match-define (list seq- (list (list y τ-elems)))
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(analyze-for-clause (syntax/loc clause [x seq])))]
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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 #`[#,y #,seq-]
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(list #`(#,y τ.norm)))]
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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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[⊢ hash-seq ≫ hash-seq- (⇒ : (~Hash K V))])
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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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(loop-clause #`[(k v) (in-hash- hash-seq-)]
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(list #'(k K) #'(v V)))]
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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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[⊢ pred ≫ pred- (⇐ : Bool)])
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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 #'pred-)]))
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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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@ -100,18 +112,29 @@
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e-body ...+) ≫
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[⊢ init ≫ init- (⇐ : τ-acc)]
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#:fail-unless (pure? #'init-) "expression must be pure"
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#:with (clauses- ([x τ] ...)) (analyze-for-clauses #'(clause.parend ...))
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[[x ≫ x- : τ] ...
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#:with (clauses- ([x x- τ] ...)) (analyze-for-clauses #'(clause.parend ...))
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[[x ≫ x-- : τ] ...
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[acc ≫ acc- : τ-acc] ⊢ (begin e-body ...) ≫ e-body-
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(⇐ : τ-acc)
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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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#:with clauses-- (substs #'(x- ...) #'(x ...) #'clauses-)
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#:with e-body-- (substs #'(x- ...) #'(x-- ...) #'e-body- free-identifier=?)
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;; #:with y (stx-car #'(x ...))
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;; #:with y- (stx-car #'(x- ...))
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;; #:with y-- (stx-car #'(x-- ...))
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;; #:with (_ (_ dbg1)) #'e-body-
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;; #:with (_ (_ dbg2)) #'e-body--
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;; #:do [(printf "y/dbg1 ~a, ~a\n" (free-identifier=? #'y #'dbg1) (bound-identifier=? #'y #'dbg1))
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;; (printf "y/dbg2 ~a, ~a\n" (free-identifier=? #'y #'dbg2) (bound-identifier=? #'y #'dbg2))
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;; (printf "y-/dbg1 ~a, ~a\n" (free-identifier=? #'y- #'dbg1) (bound-identifier=? #'y- #'dbg1))
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;; (printf "y-/dbg2 ~a, ~a\n" (free-identifier=? #'y- #'dbg2) (bound-identifier=? #'y- #'dbg2))
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;; (printf "y--/dbg1 ~a, ~a\n" (free-identifier=? #'y-- #'dbg1) (bound-identifier=? #'y-- #'dbg1))
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;; (printf "y--/dbg2 ~a, ~a\n" (free-identifier=? #'y-- #'dbg2) (bound-identifier=? #'y- #'dbg2))]
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-------------------------------------------------------
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[⊢ (for/fold- ([acc- init-])
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(#,@#'clauses--)
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e-body-)
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(#,@#'clauses-)
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e-body--)
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(⇒ : τ-acc)
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(⇒ ν-ep (τ-ep ...))
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(⇒ ν-s (τ-s ...))
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@ -57,8 +57,7 @@
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: (List (Tuple Int Int))
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⇒ (list (tuple 1 4) (tuple 2 5) (tuple 3 6)))
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;; binding in #:when isn't handled
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#;(define (zip-even [xs : (List Int)]
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(define (zip-even [xs : (List Int)]
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[ys : (List Int)])
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((inst reverse (Tuple Int Int))
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(for/fold ([acc : (List (Tuple Int Int))
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@ -66,5 +65,9 @@
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([x xs]
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#:when (even? x)
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[y ys]
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#:when (even? y))
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#:unless (odd? y))
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(cons (tuple x y) acc))))
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(check-type (zip-even (list 1 2 3) (list 5 6 7))
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: (List (Tuple Int Int))
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⇒ (list (tuple 2 6)))
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