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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
does not preserve ordering. It follows the lens laws only if you compare using
@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))
]}