In the GitHub graph, we will consider the language as categorizing the repositories. All repositories using Scala will be in the same category. For a given user, we can get the languages used by the repositories they contributed to with the following:
MATCH (:User {login: "boggle"})-[:CONTRIBUTED_TO]->(repo:Repository)-[:USES_LANGUAGE]->(lang:Language)
RETURN lang
If we want to find the other repositories using the same language, we can extend the path from the language node to the other repositories in this way:
MATCH (u:User {login: "boggle"})-[:CONTRIBUTED_TO]->(repo:Repository)-[:USES_LANGUAGE]->(lang:Language)<-[:USES_LANGUAGE]-(recommendation:Repository)
WHERE NOT EXISTS ((u)-[:CONTRIBUTED_TO]->(repo))
RETURN recommendation
For instance, the user boggle contributed to the neo4j repository, which is partly written using Scala. With that technique, we would recommend to this user the repositories neotrients...
