Hi Dennis,

I am trying to
        write and execute MAL queries. The overall goal is to translate
        Cypher to MAL and to use Cypher as an input language for
        MonetDB. I am using the "explain" statement to get some example
        MAL queries. [..]

But when I try to execute this query I get errors like
        that: ERROR = !TypeException:user.main[8]:'sql.tid' undefined
        in: C_4:bat[:oid] := sql.tid("sys":str,"sys":str,"graph":str); I
        don't know why the "X_3" is replaced by "sys". I see changes
        like that in the queries regularly.

that sounds like a bug.

Does someone
        know what is wrong or missing in this query? Thanks a lot in
        advance!

The easiest way is to put it in a file and execute it with:

    mclient -lmal -ddbname file.mal

Sometimes adding type annotations to the variables also
      helps. However, the 
*MVC*parameter should be of type
        *int*
.

Not long ago I wrote my masters thesis about a similar
      topic (also with MAL as a target language). It took me quite some
      time to figure it all out and I hope the things I collected will
      help you. I uploaded the following ( 
https://www.dropbox.com/s/v5p4ok5bhx7sud9/dsh-m5.tar.gz?dl=0
):

* Code: MAL example code, generated MAL code and benchmarks
      (mostly TPC-H and nested stuff), my project code (in Haskell),
      MonetDB extension code (in C, to write custom functions callable
      through MAL)

* Plans: PDFs with visual representations (at least the BL
      plans could interest you)

* Presentation: Could serve as a quick introduction
      (although it is very specific to Haskell/DSH and in german)

* Thesis: Many parts of it should be relevant (in english)

Best wishes,

Moritz