okram on Introducing OpenCypher, the open graph query language project

Comment on Introducing OpenCypher, the open graph query language project parent

In Gremlin3:

  g.V(blah).out("knows").aggregate("friends").
    out("knows").where(not(within("friends"))).
    select().
      by("name").
      by(count("friends")).
    order().by(valueDecr)

meowface 10y

As a developer who knows neither Cypher nor Gremlin, Cypher seems much more human-readable here, in my opinion.

    MATCH (me:User)-[:KNOWS]->(friend)-[:KNOWS]->(fof)
    WHERE NOT (me)-[:KNOWS]->(fof)

This easily reads as "get friends (AS FOF) [who know] friends [who know] me, where me [does not know] FOF" to me.

    out("knows").aggregate("friends").
    out("knows").where(not(within("friends")))

The Gremlin, on the other hand, reads as "get friends [who know] friends where... friend is not a friend???" to me.

I also don't easily see where something should be a method and where it should be a function. Why not `order(by(valueDecr))`? Why not `select("name", count("friends"))`? Why not `where(not().within("friends"))`?

okram 10y

Huh. That is a good point. In Gremlin you can chain steps together (e.g. out("knows").out("mother").out("worksFor")) and you can match patterns. So, to be clearer, I should have represented the chain as a one-liner or as a two liner with an indent.

  out("knows").aggregate("friends").out("knows").where(not(within("friends")))

  out("knows").aggregate("friends").
    out("knows").where(not(within("friends")))

Note the "." concatenation that ties the two lines together into a chain. When nesting parallel traversals (e.g. match()), the traversal patterns are delineated by ",".

  . = AND
  , = OR

Ha. Thats a generally neat way to think of "." and "," in computing. mult and + ...the algebra.

jerven 10y

FYI in SPARQL

  SELECT ?foaf
  WHERE 
  {
    ?me a <USER> .
    ?me <KNOWS> ?friend . ?friend <KNOWS> ?foaf .
    MINUS {:me <KNOWS> ?foaf }
  }

  SELECT ?foaf
  WHERE 
  {
    ?me a <USER> .
    ?me <KNOWS>/<KNOWS> ?foaf .
    MINUS {:me <KNOWS> ?foaf }
  }

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