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fix string-ith's error message; Closes PR 13197

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This commit is contained in:
Matthias Felleisen 2012-10-17 20:26:18 -04:00
parent b48d122dd7
commit f733f149f5
2 changed files with 4 additions and 4 deletions
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6
collects/lang/private/teachprims.rkt
View File

@ -482,11 +482,11 @@ namespace.
(define-teach beginner string-ith
(lambda (s n)
(define f "exact integer in [0, length of the given string]")
(cerr 'string-ith (string? s) "string" s "first")
(cerr 'string-ith (and (number? n) (integer? n) (>= n 0)) NAT n "second")
(let ([l (string-length s)])
(cerr 'string-ith (< n l) f n "second"))
(define l (string-length s))
(define f (format "exact integer in [0, ~a) (i.e., less than the length of the given string)" l))
(cerr 'string-ith (< n l) f n "second")
(string (string-ref s n))))
;; -----------------------------------------------------------------------------

2
collects/tests/htdp-lang/beg-adv.rktl
View File

@ -321,7 +321,7 @@
(htdp-err/rt-test (string-ith "hell" 4)
(exn-type-and-msg exn:fail:contract?
"string-ith: expected an exact integer in [0, length of the given string] for the second argument, but received 4"))
"string-ith: expected an exact integer in [0, 4) (i.e., less than the length of the given string) for the second argument, but received 4"))
(htdp-err/rt-test (string-ith 10 4)
(exn-type-and-msg exn:fail:contract?