3 ms·

Out of curiosity, could you share an example of how this compares to Clojure or Scala? I am not familiar with either.

markc 12y ago
Here's a quick version in Clojure. I'm sure it can be done cleaner than this.. (def articles [{:title "title1" :author "author1" :tags #{:Java :t2 :t3}} {:title "title2" :author "author1" :tags #{:Jvxa :t2 :t3}} {:title "title3" :author "author3" :tags #{:Java :t3}}]) ;; find the first article in the collection that has the tag “Java”. (first (filter #(contains? (:tags %) :Java) articles)) ;; ==> {:tags #{:t2 :Java :t3}, :title "title1", :author "author1"} ;;get all the elements that match instead of just the first (filter #(contains? (:tags %) :Java) articles) ;; ==> ({:tags #{:t2 :Java :t3}, :title "title1", :author "author1"} {:tags #{:Java :t3}, :title "title3", :author "author3"}) ;;group all the articles based on the author. (group-by :author articles) ;; cheating? ;; ==> {"author1" [{:tags #{:t2 :Java :t3}, :title "title1", :author "author1"} {:tags #{:Jvxa :t2 :t3}, :title "title2", :author "author1"}], "author3" [{:tags #{:Java :t3}, :title "title3", :author "author3"}]} ;;find all the different tags used in the collections (apply clojure.set/union (map :tags articles)) ;; ==> #{:Jvxa :t2 :Java :t3}
- codygman 12y ago
  (group-by :author articles) groupBy ((==) `on` author) articles What's wrong with cheating? :P
codygman 12y ago
formatted Scala code by hibikir from above in thread[0]: def topJavaArticle(articles:List[Article]) = articles.find(_.tags.contains("Java")) def javaArticles(articles:List[Article]) = articles.filter(_.tags.contains("Java")) def byAuthor(articles:List[Article) = articles.groupBy(_.author) 0: https://news.ycombinator.com/item?id=8874785 https://news.ycombinator.com/item?id=8874785
codygman 12y ago
I linked a Haskell version above as well: https://news.ycombinator.com/item?id=8878421 https://news.ycombinator.com/item?id=8878421

markc 12y ago

Here's a quick version in Clojure. I'm sure it can be done cleaner than this.. (def articles [{:title "title1" :author "author1" :tags #{:Java :t2 :t3}} {:title "title2" :author "author1" :tags #{:Jvxa :t2 :t3}} {:title "title3" :author "author3" :tags #{:Java :t3}}]) ;; find the first article in the collection that has the tag “Java”. (first (filter #(contains? (:tags %) :Java) articles)) ;; ==> {:tags #{:t2 :Java :t3}, :title "title1", :author "author1"} ;;get all the elements that match instead of just the first (filter #(contains? (:tags %) :Java) articles) ;; ==> ({:tags #{:t2 :Java :t3}, :title "title1", :author "author1"} {:tags #{:Java :t3}, :title "title3", :author "author3"}) ;;group all the articles based on the author. (group-by :author articles) ;; cheating? ;; ==> {"author1" [{:tags #{:t2 :Java :t3}, :title "title1", :author "author1"} {:tags #{:Jvxa :t2 :t3}, :title "title2", :author "author1"}], "author3" [{:tags #{:Java :t3}, :title "title3", :author "author3"}]} ;;find all the different tags used in the collections (apply clojure.set/union (map :tags articles)) ;; ==> #{:Jvxa :t2 :Java :t3}

codygman 12y ago
(group-by :author articles) groupBy ((==) `on` author) articles What's wrong with cheating? :P

codygman 12y ago

formatted Scala code by hibikir from above in thread[0]: def topJavaArticle(articles:List[Article]) = articles.find(_.tags.contains("Java")) def javaArticles(articles:List[Article]) = articles.filter(_.tags.contains("Java")) def byAuthor(articles:List[Article) = articles.groupBy(_.author) 0: https://news.ycombinator.com/item?id=8874785 https://news.ycombinator.com/item?id=8874785

codygman 12y ago

I linked a Haskell version above as well: https://news.ycombinator.com/item?id=8878421 https://news.ycombinator.com/item?id=8878421