One question left : Did I do this exercise the right way ?
Roelof
Op 25-6-2012 16:21, Roelof Wobben schreef:
Nope, I think I have to read the whole book to get this kind of problems.
First a lot of things to learn as lists, quote/unquote, lamba.
Roelof
Op 25-6-2012 16:14, Matthias Felleisen schreef:
This is not this kind of problem.
On Jun 25, 2012, at 10:06 AM, Richard Cleis wrote:
That is-near a better solution ;o)
I think HtDP has problems that require assembling sentences from
different parts of speech. That is a very challenging software field.
rac
On Jun 25, 2012, at 12:41 AM, Roelof Wobben wrote:
You mean something like this :
(check-expect (calculate 0 3) 3)
(define (calculate getal1 getal2)
(cond
[ (equal? getal1 0) getal2]
[ (equal? getal2 0) getal1]
[else (sqrt (+ (* getal1 getal1) (* getal2 getal2)))]
))
; String -> String
; This function produces a string depending on the input "niet " or ""
(check-expect (afdrukken "") "Het ingegeven punt is dichtbij het 0
punt")
(check-expect (afdrukken "niet ") "Het ingegeven punt is niet
dichtbij het 0 punt")
(define (afdrukken s)
(string-append first_tekst s middle_tekst)
)
; Struct -> String
; Function who outputs "niet" or a empty string depending on the
calculated distance compared with R.
(check-expect (is-near (make-posn 1 0) 5) "Het ingegeven punt is
dichtbij het 0 punt")
(check-expect (is-near (make-posn 3 4) 5) "Het ingegeven punt is
niet dichtbij het 0 punt")
(define (is-near s r)
( if (< (calculate (posn-x s) (posn-y s)) r) (afdrukken "")
(afdrukken "niet ")
))
Roelof
Op 25-6-2012 6:18, Richard Cleis schreef:
Check-expect is used to test your function.
Make that work first.
Then you can use the design recipe to make a new function.
The new function will accept the output of your first function and
return the message that you want… without any repeated words in
the function.
rac
On Jun 24, 2012, at 1:43 PM, Roelof Wobben wrote:
Hello,
This soluation is not what I was looking for.
And it uses list which I don't have learned so far.
So far I have this :
; constanten
(define R 5)
(define first_tekst "Het ingegeven punt")
(define is_tekst "is")
(define middle_tekst "dichtbij het 0 nulpunt")
(define niet "niet")
;Number Number -> Number
;This function calculates the distance of a given point compared
to the origin
(check-expect (calculate 1 0) 1)
(check-expect (calculate 3 4) 5)
(check-expect (calculate 0 3) 3)
(define (calculate getal1 getal2)
(cond
[ (equal? getal1 0) getal2]
[ (equal? getal2 0) getal1]
[else (sqrt (+ (* getal1 getal1) (* getal2 getal2)))]
))
; Struct -> String
; Function who outputs a string dependinh on the outcome of the
calculation of the distance to the origin
(check-expect (is-near (make-s 1 0) "Het ingegeven punt is
dichtbij het nulpunt"))
(check-expect (is-near (make-s 3 4) "Het ingeven punt is niet
dichtbij het nulpunt"))
(define (is-near s r)
( if (< (calculate (posn-x s) (posn-y s)) r)
Now I can do (string append first_tekst is middle-tekst) and
(string-append first-tekst is niet middle-tekst) but then I do
almost two times the same with one difference the niet part.
And Im looking for a better solution.
____________________
Racket Users list:
http://lists.racket-lang.org/users
____________________
Racket Users list:
http://lists.racket-lang.org/users
____________________
Racket Users list:
http://lists.racket-lang.org/users
