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Make assoc-lens better behaved

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This commit is contained in:
Jack Firth 2015-02-25 13:59:08 -08:00
parent f953452bf7
commit eea95c2743
1 changed files with 3 additions and 2 deletions
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5
lenses/list.rkt
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@ -68,12 +68,13 @@
(if assoc-pair
(assoc-set assoc-list key v #:is-equal? equal?)
(append assoc-list (list (list key v)))))
(values assoc-pair assoc-lens-set))
(values (and assoc-pair (second assoc-pair))
assoc-lens-set))
(module+ test
(define assoc-a-lens (assoc-lens 'a))
(define assoc-d-lens (assoc-lens 'd))
(check-equal? (lens-view assoc-a-lens assoc-list) '(a 1))
(check-equal? (lens-view assoc-a-lens assoc-list) 1)
(check-equal? (lens-set assoc-a-lens assoc-list 100)
'((a 100) (b 2) (c 3)))
(check-false (lens-view assoc-d-lens assoc-list))