Okay, Thank you.
On Fri, Jul 4, 2014 at 1:21 AM, Matthias Felleisen <matth...@ccs.neu.edu>
wrote:
>
> Yes, I corrected your program and ran into this bug.
>
> Try to use Kanren instead of Racklog. It isn't completely a legacy package
> but I doubt we can get a quick fix here.
>
> -- Matthias
>
>
>
>
> On Jul 3, 2014, at 4:53 PM, WarGrey Gyoudmon Ju wrote:
>
> Sorry, my example is not correct.
> But this one still does not work:
>
> #lang at-exp racket
>
> (require racklog)
>
> (define %edge
> (%rel ()
> [('a 'b)]
> [('b 'c)]
> [('c 'd)]
> [('d 'a)]))
>
> (define %path
> (%rel (X Y Z)
> [(X Y) (%edge X Y)]
> [(X Y) (%edge X Z) (%path Z Y)]))
>
> (let answer ([r (%which (X Y) (%path X Y))])
> (printf "~a --> ~a~n" (cdar r) (cdadr r))
> (answer (%more)))
>
> This version also will not terminate.
>
> On Thu, Jul 3, 2014 at 9:04 PM, Matthias Felleisen <matth...@ccs.neu.edu>
> wrote:
>
>>
>> If you want to learn Prolog, why not use a free Prolog implementation?
>
>
> Simply speaking, Modern Prolog seems to cut the illumos-based SunOS off, I
> cannot build it without headache and they does not answer me about this
> issue.
> So I wander if Racklog is a legacy package?
>
>
>>
>> If you want to learn about relational programming, use miniKanren, which
>> is available of cKanren. Then you can also get to constraints. Maintainer
>> cc-ed.
>>
>> -- Matthias
>>
>>
>>
>> On Jul 3, 2014, at 6:48 AM, WarGrey Gyoudmon Ju wrote:
>>
>> > This example is rewritten from the datalog version.
>> >
>> > #lang racket
>> >
>> > (require racklog)
>> >
>> > (define %edge
>> > (%rel ()
>> > [('a 'b)]
>> > [('b 'c)]
>> > [('c 'd)]
>> > [('d 'a)]))
>> >
>> > (define %path
>> > (%rel (X Y)
>> > [(X Y) (%edge X Y)]
>> > [(X Y) (%edge X 'Z)
>> > (%path 'Z Y)]))
>> >
>> > (%find-all (X Y) (%path X Y))
>> >
>> > It only gives four results.
>> >
>> > #lang racklog
>> >
>> > edge(a, b).
>> > edge(b, c).
>> > edge(c, d).
>> > edge(d, a).
>> >
>> > path(X, Y) :- edge(X, Y).
>> > path(X, Y) :- edge(X, Z), path(Z, Y).
>> >
>> > path(X, Y)?
>> >
>> > and this version will not terminate.
>> >
>> > Thanks in advance.
>> > ____________________
>> > Racket Users list:
>> > http://lists.racket-lang.org/users
>>
>>
>
>
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