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doc: fix evaluation order for parameterize

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Closes #3211
This commit is contained in:
Matthew Flatt 2020-05-24 13:10:16 -06:00
parent f66fff1ca9
commit f0c79b6b16
2 changed files with 24 additions and 5 deletions
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11
pkgs/racket-doc/scribblings/reference/parameters.scrbl
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@ -63,11 +63,12 @@ The result of a @racket[parameterize] expression is the result of the
last @racket[body]. The @racket[parameter-expr]s determine the last @racket[body]. The @racket[parameter-expr]s determine the
parameters to set, and the @racket[value-expr]s determine the parameters to set, and the @racket[value-expr]s determine the
corresponding values to install while evaluating the corresponding values to install while evaluating the
@racket[body-expr]s. All of the @racket[parameter-expr]s are evaluated @racket[body-expr]s. The @racket[parameter-expr]s and
first (and checked with @racket[parameter?]), then all @racket[value-expr]s are evaluated left-to-right (interleaved), and
@racket[value-expr]s are evaluated, and then the parameters are bound then the parameters are bound in the continuation to preserved thread
in the continuation to preserved thread cells that contain the values cells that contain the values of the @racket[value-expr]s; the result
of the @racket[value-expr]s. The last @racket[body-expr] is in tail of each @racket[parameter-expr] is checked with @racket[parameter?]
just before it is bound. The last @racket[body-expr] is in tail
position with respect to the entire @racket[parameterize] form. position with respect to the entire @racket[parameterize] form.
Outside the dynamic extent of a @racket[parameterize] expression, Outside the dynamic extent of a @racket[parameterize] expression,

18
pkgs/racket-test-core/tests/racket/syntax.rktl
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@ -1269,6 +1269,24 @@
(error-test #'(parameterize ([(lambda (a) 10) 10]) 8)) (error-test #'(parameterize ([(lambda (a) 10) 10]) 8))
(error-test #'(parameterize ([(lambda (a b) 10) 10]) 8)) (error-test #'(parameterize ([(lambda (a b) 10) 10]) 8))
;; Check documented order of evaluation
(let ([str (let ([o (open-output-string)])
(define p1 (make-parameter 1 (λ (x) (displayln "p1" o) x)))
(define p2 (make-parameter 2 (λ (x) (displayln "p2" o) x)))
(parameterize ([(begin (displayln "b1" o) p1) (begin (displayln "a1" o) 4)]
[(begin (displayln "b2" o) p2) (begin (displayln "a2" o) 5)])
3)
(get-output-string o))])
(test "b1\na1\nb2\na2\np1\np2\n" values str))
(let ([str (let ([o (open-output-string)])
(define p1 (make-parameter 1 (λ (x) (displayln "p1" o) x)))
(err/rt-test/once
(parameterize ([(begin (displayln "b1" o) p1) (begin (displayln "a1" o) 4)]
[(begin (displayln "b2" o) 'no) (begin (displayln "a2" o) 5)])
3))
(get-output-string o))])
(test "b1\na1\nb2\na2\np1\n" values str))
(test 1 'time (time 1)) (test 1 'time (time 1))
(test -1 'time (time (cons 1 2) -1)) (test -1 'time (time (cons 1 2) -1))
(test-values '(-1 1) (lambda () (time (values -1 1)))) (test-values '(-1 1) (lambda () (time (values -1 1))))