Re: core.logic merge substitutions map?
Thanks for the advice and code-snippet. On Monday, November 18, 2013 7:43:12 PM UTC-8, Norman Richards wrote: On Mon, Nov 18, 2013 at 6:26 PM, Kevin Downey red...@gmail.comjavascript: wrote: https://github.com/sonian/Greenmail/blob/master/src/clj/greenmail/db.clj#L98-L126 has an example, using clojure.core.logic/all to make a goal which is a conjunction of the clojure.core.logic/== goals Based on my experience writing pldb, using == in this situation is going to work better than using unify as shown in the code sample base on the video. I found that using unify for this type of custom relation appears to work but will not do the right thing with more complicated situations. I found constraints particularly problematic. Switching from unify to == makes sure everything you want to happen on unify actually happens. -- -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en --- You received this message because you are subscribed to the Google Groups Clojure group. To unsubscribe from this group and stop receiving emails from it, send an email to clojure+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/groups/opt_out.
Re: core.logic merge substitutions map?
https://github.com/sonian/Greenmail/blob/master/src/clj/greenmail/db.clj#L98-L126 has an example, using clojure.core.logic/all to make a goal which is a conjunction of the clojure.core.logic/== goals On 11/16/13, 5:04 PM, Mark wrote: d'oh! Answering my own question: Just compose the unify functions a la (unify (unify a v1 (:v1 r) v2 (:v2 r)) I have a feeling there is a library function/macro that would make this less messy but I can't find it from the cheatsheet. On Saturday, November 16, 2013 10:31:50 AM UTC-8, Mark wrote: I stumbled across Timothy Baldridge's excellent video http://www.youtube.com/watch?v=HHZ8iqswiCwexplaining how to incorporate data sources into core.logic. It reinvigorated my interest in using core.logic to query SQL RDBMS. I'm stumbling on a pretty simple thing, I think. I've got a table that has three columns, a single primary key column and two value columns. Using the pattern Tim outlines in his video, I've got a relation function that takes three parameters, one for each column and I'm trying to work through the case where the primary key is ground and the value columns are lvars. This translates to a query of the form SELECT v1, v2 FROM t WHERE pkey=?. Of course, this returns two values that must be unified. That's where I'm stuck. I know I want to return a substitution map, but I have two lvars to unify. How do I merge the two substitution maps? Sample code: (defn pkey-v1-v2-o [pkey v1 v2] (fn [a] (let [pkey (walk a pkey) v1 (walk a v1) v2(walk a v2)] (condp = [(not (lvar? pkey)) (not (lvar? v1)) (not (lvar? v2))] [true false false ] (to-stream (let [r (first (query [SELECT v1, v2 FROM T WHERE pkey=? pkey]))] (some-merge-fn (unify a v1 (:v1 r)) (unify a v2 (:v2 r) -- And what is good, Phaedrus, And what is not good— Need we ask anyone to tell us these things? signature.asc Description: OpenPGP digital signature
Re: core.logic merge substitutions map?
On Mon, Nov 18, 2013 at 6:26 PM, Kevin Downey redc...@gmail.com wrote: https://github.com/sonian/Greenmail/blob/master/src/clj/greenmail/db.clj#L98-L126 has an example, using clojure.core.logic/all to make a goal which is a conjunction of the clojure.core.logic/== goals Based on my experience writing pldb, using == in this situation is going to work better than using unify as shown in the code sample base on the video. I found that using unify for this type of custom relation appears to work but will not do the right thing with more complicated situations. I found constraints particularly problematic. Switching from unify to == makes sure everything you want to happen on unify actually happens. -- -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en --- You received this message because you are subscribed to the Google Groups Clojure group. To unsubscribe from this group and stop receiving emails from it, send an email to clojure+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/groups/opt_out.
core.logic merge substitutions map?
I stumbled across Timothy Baldridge's excellent video http://www.youtube.com/watch?v=HHZ8iqswiCwexplaining how to incorporate data sources into core.logic. It reinvigorated my interest in using core.logic to query SQL RDBMS. I'm stumbling on a pretty simple thing, I think. I've got a table that has three columns, a single primary key column and two value columns. Using the pattern Tim outlines in his video, I've got a relation function that takes three parameters, one for each column and I'm trying to work through the case where the primary key is ground and the value columns are lvars. This translates to a query of the form SELECT v1, v2 FROM t WHERE pkey=?. Of course, this returns two values that must be unified. That's where I'm stuck. I know I want to return a substitution map, but I have two lvars to unify. How do I merge the two substitution maps? Sample code: (defn pkey-v1-v2-o [pkey v1 v2] (fn [a] (let [pkey (walk a pkey) v1 (walk a v1) v2(walk a v2)] (condp = [(not (lvar? pkey)) (not (lvar? v1)) (not (lvar? v2))] [true false false ] (to-stream (let [r (first (query [SELECT v1, v2 FROM T WHERE pkey=? pkey]))] (some-merge-fn (unify a v1 (:v1 r)) (unify a v2 (:v2 r) -- -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en --- You received this message because you are subscribed to the Google Groups Clojure group. To unsubscribe from this group and stop receiving emails from it, send an email to clojure+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/groups/opt_out.
Re: core.logic merge substitutions map?
d'oh! Answering my own question: Just compose the unify functions a la (unify (unify a v1 (:v1 r) v2 (:v2 r)) I have a feeling there is a library function/macro that would make this less messy but I can't find it from the cheatsheet. On Saturday, November 16, 2013 10:31:50 AM UTC-8, Mark wrote: I stumbled across Timothy Baldridge's excellent video http://www.youtube.com/watch?v=HHZ8iqswiCwexplaining how to incorporate data sources into core.logic. It reinvigorated my interest in using core.logic to query SQL RDBMS. I'm stumbling on a pretty simple thing, I think. I've got a table that has three columns, a single primary key column and two value columns. Using the pattern Tim outlines in his video, I've got a relation function that takes three parameters, one for each column and I'm trying to work through the case where the primary key is ground and the value columns are lvars. This translates to a query of the form SELECT v1, v2 FROM t WHERE pkey=?. Of course, this returns two values that must be unified. That's where I'm stuck. I know I want to return a substitution map, but I have two lvars to unify. How do I merge the two substitution maps? Sample code: (defn pkey-v1-v2-o [pkey v1 v2] (fn [a] (let [pkey (walk a pkey) v1 (walk a v1) v2(walk a v2)] (condp = [(not (lvar? pkey)) (not (lvar? v1)) (not (lvar? v2))] [true false false ] (to-stream (let [r (first (query [SELECT v1, v2 FROM T WHERE pkey=? pkey]))] (some-merge-fn (unify a v1 (:v1 r)) (unify a v2 (:v2 r) -- -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en --- You received this message because you are subscribed to the Google Groups Clojure group. To unsubscribe from this group and stop receiving emails from it, send an email to clojure+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/groups/opt_out.
