dan[mlpack]$ ls
foo/  foo.mlpack
dan[mlpack]$ ls foo
bar.ml	baz.ml
dan[mlpack]$ cat foo.mlpack
Bar
Baz

dan[mlpack]$ ocamlbuild foo.cmo
Solver failed:
  Ocamlbuild cannot find or build foo.ml.  A file with such a name would usually be a source file.  I suspect you have given a wrong target name to Ocamlbuild.
Backtrace:
  - Failed to build the target foo.cmo
      - Building foo.cmo:
          - Failed to build all of these:
              - Building foo.ml:
                  - Failed to build all of these:
                      - Building foo.mly
                      - Building foo.mll
              - Building foo.mli:
                  - Building foo.mly
              - Failed to build all of these:
                  - Building Bar.cmi:
                      - Failed to build all of these:
                          - Building Bar.ml
                          - Building Bar.mlpack
                          - Building Bar.mli:
                              - Building Bar.mly
                  - Building bar.cmi:
                      - Failed to build all of these:
                          - Building bar.ml
                          - Building bar.mlpack
                          - Building bar.mli:
                              - Building bar.mly
                  - Building Bar.cmo:
                      - Failed to build all of these:
                          - Building Bar.ml:
                              - Failed to build all of these:
                                  - Building Bar.mly
                                  - Building Bar.mll
                          - Building Bar.mli:
                              - Building Bar.mly
                          - Building Bar.mlpack
                          - Building Bar.mli:
                              - Building Bar.mly
                  - Building bar.cmo:
                      - Failed to build all of these:
                          - Building bar.ml:
                              - Failed to build all of these:
                                  - Building bar.mly
                                  - Building bar.mll
                          - Building bar.mli:
                              - Building bar.mly
                          - Building bar.mlpack
                          - Building bar.mli:
                              - Building bar.mly
              - Building foo.mli:
                  - Building foo.mly
Compilation unsuccessful after building 0 targets (0 cached) in 00:00:00.
dan[mlpack]$