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second draft of char/string

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svn: r14755
This commit is contained in:
Matthias Felleisen 2009-05-08 21:55:05 +00:00
parent 7ad3d7b4a6
commit bac292acc6
1 changed files with 36 additions and 88 deletions
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124
collects/lang/private/todo.ss
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@ -1,10 +1,5 @@
#lang scheme
;; If we eliminate char from HtDP/I, we need to add re-think
;; the following functions. Concrete proposals attached.
;; If you're in a hurry, look for QQQ.
#| QQQ: okay?
char-upcase: use string-upcase instead
char-downcase: use string-downcase instead
@ -83,20 +78,17 @@ substring consumes 2 or 3 arguments
(string (string-ref s n))))
;; -----------------------------------------------------------------------------
;; QQQ: this would be a re-definition of a Scheme function. Should we rename?
(check-expect (beginner-make-string 3 "a") "aaa")
(check-error
(beginner-make-string 3 "ab")
(string-append "make-string: " 1-letter " expected, given "
(format "~s" "ab")))
(check-expect (beginner-replicate 3 "a") "aaa")
(check-expect (beginner-replicate 3 "ab") "ababab")
(check-error (beginner-replicate 3 10) "replicate: string expected, given 10")
(define-teach beginner make-string
(define-teach beginner replicate
(lambda (n s1)
(unless (and (number? n) (exact-integer? n) (>= n 0))
(error 'make-string "(exact) natural number expected, given ~e" n))
(unless (1-letter? 'make-string s1)
(error 'make-string "~a expected, given ~e" 1-letter s1))
(error 'replicate "(exact) natural number expected, given ~e" n))
(unless (string? s1)
(error 'replicate "string expected, given ~e" s1))
(apply string-append (build-list n (lambda (i) s1)))))
;; -----------------------------------------------------------------------------
@ -126,14 +118,10 @@ substring consumes 2 or 3 arguments
(check-expect (beginner-string->int "A") 65)
(check-error
(beginner-string->int 10)
(string-append
"string->int: " 1-letter " expected, not a string: "
"10"))
(string-append "string->int: " 1-letter " expected, not a string: 10"))
(check-error
(beginner-string->int "AB")
(string-append
"string->int: " 1-letter " expected, given "
(format "~s" "AB")))
(string-append "string->int: " 1-letter " expected, given " (format "~s" "AB")))
(define-teach beginner string->int
(lambda (s)
@ -144,11 +132,8 @@ substring consumes 2 or 3 arguments
;; -----------------------------------------------------------------------------
(check-expect (beginner-explode "hello") (list "h" "e" "l" "l" "o"))
(check-error
(beginner-explode 10)
(string-append
"explode: string expected, given "
"10"))
(check-error (beginner-explode 10)
(string-append "explode: string expected, given " "10"))
(define-teach beginner explode
(lambda (s)
@ -159,60 +144,48 @@ substring consumes 2 or 3 arguments
;; -----------------------------------------------------------------------------
(check-expect (beginner-implode (list "h" "e" "l" "l" "o")) "hello")
(check-error
(beginner-implode 10)
(string-append
"implode: list of " 1-letter* " expected, not a list: "
"10"))
(check-error
(beginner-implode '("he" "l"))
(string-append
"implode: list of " 1-letter* " expected, given "
(format "~s" '("he" "l"))))
(check-error (beginner-implode 10)
(string-append "implode: list of " 1-letter*
" expected, not a list: 10"))
(check-error (beginner-implode '("he" "l"))
(string-append "implode: list of " 1-letter* " expected, given "
(format "~s" '("he" "l"))))
(define-teach beginner implode
(lambda (los)
(unless (1-letter*? 'implode los)
(error 'implode "list of ~a expected, given ~e" 1-letter* los))
(list->string (map (lambda (s) (string-ref s 0)) los))))
(apply string-append los)))
;; -----------------------------------------------------------------------------
(check-expect (beginner-string1-numeric? "0") true)
(check-expect (beginner-string1-numeric? "a") false)
(check-error
(beginner-string1-numeric? "ab")
(string-append "string1-numeric?: " 1-letter " expected, given "
(format "~s" "ab")))
(check-expect (beginner-string-numeric? "0") true)
(check-expect (beginner-string-numeric? "10") true)
(check-expect (beginner-string-numeric? "a") false)
(check-expect (beginner-string-numeric? "ab") false)
(check-error (beginner-string-numeric? 10)
(string-append "string-numeric?: string expected, given 10"))
(define-teach beginner string1-numeric?
(define-teach beginner string-numeric?
;; is this: (number? (string->number s)) enough?
(lambda (s1)
(unless (1-letter? 'string1-numeric? s1)
(error 'string1-numeric? "~a expected, given ~e" 1-letter s1))
(char-numeric? (string-ref s1 0))))
(unless (string? s1)
(error 'string-numeric? "string expected, given ~e" s1))
(andmap char-numeric? (string->list s1))))
;; -----------------------------------------------------------------------------
;; I used copying here and I feel awful.
(check-expect (beginner-string1-alphabetic? "0") false)
(check-expect (beginner-string1-alphabetic? "a") true)
(check-error
(beginner-string1-alphabetic? "ab")
(string-append "string1-alphabetic?: " 1-letter " expected, given "
(format "~s" "ab")))
(check-expect (beginner-string-alphabetic? "a0") false)
(check-expect (beginner-string-alphabetic? "a") true)
(check-expect (beginner-string-alphabetic? "ba") true)
(check-expect (beginner-string-alphabetic? "ab") true)
(define-teach beginner string1-alphabetic?
;; is this
#;
(andmap (lambda (c)
(or (string<=? "A" x "Z") (string<=? "a" x "z")))
(string->list s))
;; enough?
(define-teach beginner string-alphabetic?
(lambda (s1)
(unless (1-letter? 'string1-alphabetic? s1)
(error 'string1-alphabetic? "~a expected, given ~e" 1-letter s1))
(char-alphabetic? (string-ref s1 0))))
(unless (string? s1)
(error 'string-alphabetic? "string expected, given ~e" s1))
(andmap char-alphabetic? (string->list s1))))
;; -----------------------------------------------------------------------------
@ -252,29 +225,4 @@ substring consumes 2 or 3 arguments
;; -----------------------------------------------------------------------------
;; !!! redefinition !!! (and copy from teachprims.ss)
;; QQQ: do we need a new name????
(check-expect (intermediate-build-string 3 (lambda (x) "x")) "xxx")
(define-teach intermediate build-string
(lambda (n f)
(unless (and (number? n) (integer? n) (>= n 0))
(error 'build-string
"first argument must be of type <natural number>, given ~e"
n))
(unless (and (procedure? f) (procedure-arity-includes? f 1))
(error 'build-string
"second argument must be a <procedure> that accepts one argument, given ~e"
f))
(apply string-append
(build-list
n
(lambda (i)
(define r (f i))
(unless (1-letter? 'build-string r)
(error 'build-string
"second argument must be a <procedure> that produces a ~a, given ~e, which produced ~e for ~e"
1-letter f r i))
r)))))
(test)