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memoize the creation of the name in the blame object

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Robby Findler 2018-05-02 18:53:48 -05:00
parent 822938d9ae
commit 3f4cbcbfd8
1 changed files with 8 additions and 1 deletions
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9
racket/collects/racket/contract/private/blame.rkt
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@ -76,10 +76,17 @@
(unless positive (unless positive
(raise-type-error 'make-blame "(not/c #f)" 3 (raise-type-error 'make-blame "(not/c #f)" 3
source value build-name positive negative original?)) source value build-name positive negative original?))
(define build/memo-name
(let* ([uniq (box #f)]
[ans uniq])
(λ ()
(when (eq? uniq ans)
(set! ans (build-name)))
ans)))
(make-blame (make-blame
source source
value value
build-name build/memo-name
(list positive) (list positive)
(and negative (list negative)) (and negative (list negative))
original? original?