gistfile1.txt

$ cat project.qbp 
import qbs.base 1.0

Project { 
  moduleSearchPaths: "."
  Application {
           name: "helloworld"
           files: ["code.ml"]//, "gamemap.cpp", "main.cpp" ]
           Depends { name: "Qt.core" }
           Depends { name: "cpp" }
           Depends { name: "Qt.declarative" }
           Depends { name: "ocaml" }
  }
}
$ cat ocaml/OCamlModule.qbs 
import qbs.base 1.0

Module {
  name: "ocaml"
  FileTagger {
    pattern: "*.ml"
    fileTags: ["ml"]
  }
  Rule {
//    id: compile
    inputs: ["ml"]
    multiplex: true
    Artifact {
      fileName: input.basename + '.cmo'
      fileTags: ["cmo"]
    }
    prepare: {
            var cmd = new Command("ocaml -c", [input.basename] );
            return cmd;      
      
    }
  }
}
$ rm -rf build && qbs
Found project file /media/disk/kakadu/prog/lablqt/qml/test2qbs/project.qbp
loading project took:  107 ms 
ERROR: No artifacts generated for product 'helloworld'.