Hmm, I didn't explain it very well. What if I had more knowledge?
Maybe I knew two grades sometimes. That could cut down on the list of
possible students (assuming there are more than the three in my
example).
How could I write a function that worked for both of these cases?
(matches [{:course 'Algebra :g 'B}])
(matches [{:course 'Algebra :g 'B} {:course 'Art :g 'C}])
On Sat, May 19, 2012 at 2:02 PM, David Nolen <dnolen.li...@gmail.com> wrote:
> I don't think you need to generate goals for something as straightforward as
> this:
>
> (defrel grade person course g)
> (fact grade 'Bob 'Algebra 'B)
> (fact grade 'Bob 'Art 'C)
> (fact grade 'John 'Algebra 'A)
> (fact grade 'John 'Art 'A)
> (fact grade 'Ricky 'Algebra 'D)
> (fact grade 'Ricky 'Art 'A)
>
> (defn matches [{:keys [course g]}]
> (run* [q]
> (fresh [p]
> (grade p course g)
> (== q [p course g]))))
>
> (matches {:course 'Algebra :g 'B})
>
> On Sat, May 19, 2012 at 2:12 PM, Alex Robbins
> <alexander.j.robb...@gmail.com> wrote:
>>
>> I'm just getting started with logic programming, and it is entirely
>> possible I'm just approaching this incorrectly.
>>
>> Is it possible to use dynamically generated goals in run* ?
>>
>> For example,
>>
>> (defrel grade person course g)
>> (fact grade 'Bob 'Algebra 'B)
>> (fact grade 'Bob 'Art 'C)
>> (fact grade 'John 'Algebra 'A)
>> (fact grade 'John 'Art 'A)
>> (fact grade 'Ricky 'Algebra 'D)
>> (fact grade 'Ricky 'Art 'A)
>>
>> (def knowledge
>> {:course 'Algebra :g 'B})
>>
>> (defn generate-goals [knowledge]
>> (map
>> (fn [{:keys [course g]}] (list 'grade 'person course g))
>> knowledge))
>>
>> I want to do something like this (but valid clojure):
>> (run* [person]
>> ~@(generate-goals knowledge))
>>
>> It should give me back a list of people who match my current
>> knowledge. If I have more knowledge about the person, it will generate
>> more conditions, less knowledge fewer conditions. However, since run*
>> and run are macros, I can't apply them to a list. I can't splice in
>> because I'm not in a quotes list. Any ideas?
>>
>> Thanks!
>>
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>
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