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clarify error message for take and drop (#1582)

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Benjamin Greenman 2017-03-06 18:45:09 -05:00 committed by GitHub
parent b978631823
commit 6e746891ef
1 changed files with 7 additions and 10 deletions
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17
racket/collects/racket/list.rkt
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@ -144,16 +144,13 @@
(define (drop* list n) ; no error checking, returns #f if index is too large (define (drop* list n) ; no error checking, returns #f if index is too large
(if (zero? n) list (and (pair? list) (drop* (cdr list) (sub1 n))))) (if (zero? n) list (and (pair? list) (drop* (cdr list) (sub1 n)))))
(define (too-large who list n) (define (too-large who list n)
(raise-arguments-error (define proper? (list? list))
who (raise-argument-error who
(if (list? list) (format "a ~alist with at least ~a ~a"
"index is too large for list" (if proper? "" "(possibly improper) ")
"index reaches a non-pair") n
"index" n (if proper? "elements" "pairs"))
(if (list? list) list))
"list"
"in")
list))
(define (take list0 n0) (define (take list0 n0)
(unless (exact-nonnegative-integer? n0) (unless (exact-nonnegative-integer? n0)