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add examples of set-filterer-lens on lists and set=?

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AlexKnauth 2015-08-21 14:49:45 -04:00
parent 109495d23c
commit 86689171d9
1 changed files with 8 additions and 1 deletions
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9
unstable/lens/set-filterer.scrbl
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@ -15,4 +15,11 @@ Creates a lens that filters a set by the predicate @racket[pred].
Lists are also sets, so @racket[set-filterer-lens] works for lists too, but it Lists are also sets, so @racket[set-filterer-lens] works for lists too, but it
does not preserve ordering. It follows the lens laws only if you compare using does not preserve ordering. It follows the lens laws only if you compare using
@racket[set=?], not @racket[equal?]. @racket[set=?], not @racket[equal?].
} @lenses-unstable-examples[
(lens-view (set-filterer-lens number?) '(a 1 2 3)) ; will be '(1 2 3)
(lens-set (set-filterer-lens number?) '(a 1 2 3) '(1 2 3)) ; will be '(3 2 1 a)
(code:comment "this breaks the lens laws according to equal?")
(equal? '(a 1 2 3) '(3 2 1 a))
(code:comment "but not according to set=?")
(set=? '(a 1 2 3) '(3 2 1 a))
]}