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add more checking to the bst/c example

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This commit is contained in:
Robby Findler 2020-05-22 20:54:53 -05:00
parent cc9514c290
commit d590eee0c7
1 changed files with 20 additions and 7 deletions
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27
pkgs/racket-doc/scribblings/reference/contracts.scrbl
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@ -773,13 +773,26 @@ The lazy annotations ensure that this contract does not
change the running time of operations that do not
inspect the entire tree.
@racketblock[(struct bt (val left right))
(define (bst/c lo hi)
(or/c #f
(struct/dc bt
[val (between/c lo hi)]
[left (val) #:lazy (bst/c lo val)]
[right (val) #:lazy (bst/c val hi)])))]
@examples[#:eval (contract-eval) #:once
(struct bt (val left right))
(define (bst/c lo hi)
(or/c #f
(struct/dc bt
[val (between/c lo hi)]
[left (val) #:lazy (bst/c lo val)]
[right (val) #:lazy (bst/c val hi)])))
(define/contract not-really-a-bst
(bst/c -inf.0 +inf.0)
(bt 5
(bt 4
(bt 2 #f #f)
(bt 6 #f #f))
#f))
(bt-right not-really-a-bst)
(bt-val (bt-left (bt-left not-really-a-bst)))
(eval:error (bt-right (bt-left not-really-a-bst)))]
@history[#:changed "6.0.1.6" @elem{Added @racket[#:inv].}]
}