Thanks for your suggestion, didn't know about that! One of the things that made someone say that "Clojure looks like a language from the near future". However, I'm having a hard time using it with its full power. Could you recommend any other resource, besides the overview page on github, to learn pattern matching? Maybe a project that uses them?
For the record, my code uses a simple truth table now: (defn add-edge ([g v1 v2 & vs] (add-edge g (concat [v1 v2] vs))) ([g edge] (let [two? (= 2 (count edge)) dist? (apply distinct? edge) e (match [(hyper? g) (looped? g)] ; e will be nil if edge is invalid for this graph [false false] (when (and two? dist?) edge) [false true ] (when two? edge) [true false] (when dist? edge) [true true ] edge] (if e (update-in g [:edges] conj (if (directed? g) (vec e) (set e))) g)))) On Wednesday, September 4, 2013 7:07:06 PM UTC-3, Leonardo Borges wrote: > > You could use pattern matching with core.match > On 05/09/2013 6:57 AM, "Bruno Kim Medeiros Cesar" > <bruno...@gmail.com<javascript:>> > wrote: > >> I'm writing (another) basic graph library, and would like to treat inputs >> depending on the type of the graph. A graph can be >> >> - Directed, in which case edges are vectors. Otherwise, edges are >> sets; >> - Looped, allowing edges from a node to itself; >> - Pseudo (or multi), allowing multiples edges between the same >> endpoints; and >> - Hyper, allowing edges with more than two vertices. >> >> To illustrate better these characteristics you can think of a scientific >> publication network as a directed, looped, pseudo-hypergraph. Vertices are >> authors, and edges are articles containing multiple researchers (hyper) who >> can publish alone (looped). There are multiple articles between the same >> researchers (pseudo) and in some contexts author order matters (directed). >> >> Now, I've created a flowchart <http://imgur.com/IdgsGFG> to decide if an >> edge should be conjed in a graph :edges entry, that leads to the following >> straightforward function: >> (defn add-edge >> ([graph v1 v2 & vs] (add-edge graph (concat [v1 v2] vs))) >> ([graph edge] >> (if (and (multi? graph) (not= 2 (count edge))) >> graph >> (if (and (looped? graph) (not (distinct? edge))) >> graph >> (let [e (if (directed? edge) (vec edge) (set edge))] >> (update-in graph [:edges] conj e)))))) >> >> That looks ugly and a pattern that could propagate in a codebase. So I >> tried to factor out multimethods from it, and ended with the following: >> >> (defmulti ^:private add-edge0 (fn [g e] (hyper? g))) >> (defmulti ^:private add-edge1 (fn [g e] (looped? g))) >> (defmulti ^:private add-edge2 (fn [g e] (directed? g))) >> (defn ^:private add-edge3 [g e] >> (update-in g [:edges] conj e)) >> >> (defmethod add-edge0 :hyper [g e] (add-edge1 g e)) >> (defmethod add-edge0 :default [g e] (if (= 2 (count e)) >> (add-edge1 g e) >> g)) >> (defmethod add-edge1 :looped [g e] (add-edge2 g e)) >> (defmethod add-edge1 :default [g e] (if (distinct? e) >> (add-edge2 g e) >> g)) >> (defmethod add-edge2 :directed [g e] (add-edge3 g (vec e))) >> (defmethod add-edge2 :default [g e] (add-edge3 g (set e))) >> >> (defn add-edge >> ([g v1 v2 & vs] (add-edge g (concat [v1 v2] vs))) >> ([g edge] (add-edge0 g edge))) >> >> That doesn't look much better, as the amount of boilerplate increased, >> but at least the concerns for each type are separated. >> >> Do you have any suggestions on how to improve this design? Thanks for any >> consideration! >> >> Bruno Kim Medeiros Cesar >> Engenheiro de Computação >> Pesquisador em Redes Complexas >> www.brunokim.com.br >> >> -- >> -- >> You received this message because you are subscribed to the Google >> Groups "Clojure" group. >> To post to this group, send email to clo...@googlegroups.com<javascript:> >> Note that posts from new members are moderated - please be patient with >> your first post. >> To unsubscribe from this group, send email to >> clojure+u...@googlegroups.com <javascript:> >> 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+u...@googlegroups.com <javascript:>. >> For more options, visit https://groups.google.com/groups/opt_out. >> > -- -- 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.