Or:
(build-list n (lambda (dont-care) (make-random-string)))
On Tue, Oct 25, 2016 at 10:42 PM, Robby Findler <ro...@eecs.northwestern.edu
> wrote:
> I would probably write that function like this:
>
> #lang racket
>
> (provide
> (contract-out
> [make-a-string (-> non-empty-string? string?)]))
>
> (define (make-a-string candidates)
> (apply
> string
> (for/list ([i (in-range (random 100))])
> (string-ref candidates (random (string-length candidates))))))
>
> (module+ test
> (require rackunit)
> (check-true (string? (make-a-string "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123
> 456789"))))
>
>
> hth,
> Robby
>
>
> On Tue, Oct 25, 2016 at 9:39 PM, <meino.cra...@gmx.de> wrote:
> > Hi,
> >
> > I want to create a list of random strings.
> > For that I have created a function, which returns a string
> > of random length and random contents.
> >
> > Then I used
> > make-list n (make-random-string)
> >
> > to create that list....and get back a list filled with n
> > identical strings.
> >
> > hmmmm...
> >
> > make-list calls make-random-string ones and the rest
> > is repetition.
> >
> > If I think to have understood correctly for-loops and such are
> > somehow of "imperative, non-functional old-school programming style"
> > and map/apply and friends are the tools of the real racket programmer
> > ;) this lead to a more general "problem" ("problem" only for a newbie
> > like me may be)...:
> >
> > Since make-list calls its list-argument only once, the above does not
> > work in the sense it is wanted, so make-list creates only lists of
> > the same thing.
> >
> > Therefore to prevent "for" and friends, I have to call make-list
> > with the empty list as list-argument and then map the
> > make-random-string to each of them, which ensures that
> > make-random-string is not called once.
> > That feels ugly.
> >
> > What is a good "racket-ish" of "racket-y" way (nothing negative
> > meant...just a play with words by someone, who is no native
> > speaker...;) to do something n times without old-school
> > for-and-friends-loops.
> >
> > Here is the code:
> >
> > #lang racket
> > (require racket/random)
> > (require racket/string)
> >
> > (define charseq "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789" )
> > (define minchars 7)
> > (define maxchars 15)
> > (define numlists 6)
> >
> > (define (make-random-string seq min max)
> > ( let ((lenstr (random min max)))
> > ( apply string (random-sample seq lenstr))))
> >
> > (define (make-list-of-random-strings cnt seq min max )
> > (make-list cnt (make-random-string seq min max )))
> >
> > (define (make-list-of-lists numsublists)
> > ( make-list numsublists (make-list-of-random-strings numlists charseq
> minchars maxchars)))
> >
> > ( define (main)
> > (make-list-of-lists 20))
> >
> > (main)
> >
> > Any improvement is welcome!
> >
> > Cheers,
> > Meino
> >
> >
> >
> > --
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