It's common misconception that core.logic is a bunch of macros. The macros
are just sugar, there are functions for *everything*.
You can load a stream of "facts" however you please, you should look at
`to-stream` which can take any Clojure sequence of data and make it useable
from core.logic as a list of facts. Note this is very naive - you'll have
to provide indexing yourself if you have a large data set. You might want
to take a look at the experimental Datomic integration notes on the
core.logic wiki for further guidance.
I would look into this approach first and see if this doesn't answer your
other questions as well.
David
On Fri, Jun 21, 2013 at 11:28 AM, Karsten Schmidt <i...@toxi.co.uk> wrote:
> Hi all, am toying around with the thought of generating core.logic
> queries dynamically. However, I'm stuck at square one since all
> the core.logic functions are macros and am not sure how to refer
> to logic vars within a query generator fn.
>
> E.g. given this list of facts...
>
> (def myfacts
> [[:karsten :spouse :mia]
> [:fred :spouse :anna]
> [:mia :name "mia"]
> [:anna :name "anna"]])
>
> ...I'd like to find the person who's spouse's name is "mia".
>
> The SPARQL[1] equivalent for the above would be:
> SELECT ?p WHERE { ?p :spouse ?s . ?s :name "mia" }
>
> In core.logic I can do this equivalently, but have no idea how to
> generate the lists of `conso`s dynamically:
>
> (run* [p]
> (fresh [s]
> (conde
> [(conso p [:spouse s] (myfacts 0))]
> [(conso p [:spouse s] (myfacts 1))]
> [(conso p [:spouse s] (myfacts 2))]
> [(conso p [:spouse s] (myfacts 3))])
> (conde
> [(conso s [:name "mia"] (myfacts 0))]
> [(conso s [:name "mia"] (myfacts 1))]
> [(conso s [:name "mia"] (myfacts 2))]
> [(conso s [:name "mia"] (myfacts 3))])))
>
> ; => (:karsten)
>
> a) How would I go about generating such a single `conso` only given a
> single logic var, var position in the triple and the fact triple
> itself?
>
> b) How can I refer to a logic var in a function outside the lexical
> scope of `fresh` or `run*`?
>
> c) What is the best way to produce and pass a seq of goals for `conde`?
> Since
> it is a macro I can't use `apply`...
>
> K.
>
> [1] http://www.w3.org/TR/sparql11-overview/
>
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