On Wednesday, March 8, 2017 at 1:43:56 AM UTC+1, Evgenii Moiseenko wrote:
>
> I was wondering how the implementation of map-like data structure should
> look like in MiniKanren. I am writing an interpreter of imperative language
> in MiniKanren and I need a data structure to represent a mappings between
> variables and their values.
>
> Is there any code that implements that ?
>
Sorry, I don't have a direct answer but I'd like to share my findings
regarding this topic.
So, microkanren does support relational in my implementation but you always
need to
ask explicitly to cross a relation, which is translated by variable forming
a cross in the
scheme expression. For instance the following:
(run* (strawberry)
(fresh is fresh?)
(fs fruit 'concept/name "fruit")
(fs is 'relation/start fruit)
(fs is 'relation "is")
(fs is 'relation/end concept)))
the database doesn't know that a feature is another feature. Simply said,
foreign keys
are represented as keys. If you follow foreign keys automatically, you
don't know where
it ends it's like a http redirect (302) in the hole of the white rabbit.
That said, I think it could be made less painful using the unify procedure
of feature strucutres,
does basically that:
(define-module (space-feature))
(define database (sf:open "memory://"))
(define fruit (add! database '((kind . concept)
(concept . fruit))))
(define strawberry (add! database '((kind . concept)
(concept . strawberry))))
(define strawberry-is-a-fruit (add! database `((kind . relation)
(start . ,strawberry)
(relation . is)
(end . ,fruit))))
(define what-is-a-fruit (unify database `((kind . relation)
(relation . is)
(end . ,fruit))))
(pk (equals? what-is-a-fruit `(((kind . relation)
(relation . is)
(end . ,fruit)
(start . ,strawberry))))
(pk (equals? (ref strawberry) '((kind . concept)
(concept . strawberry))))
;; but also
(define what-is-a-fruit (unify database `((kind . relation)
(relation . is)
(end . (@ ((kind . concept)))))))
(pk (equals? what-is-a-fruit `(((kind . relation)
(relation . is)
(end . ,fruit)
(start . (@ '((kind . concept)
(concept . strawberry))))))))
That's kind of the "API" of GraphQL.
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