How to include data file in dune build for OCaml program?

Question

I have a project where myprogram.ml depends on an external data file, mydata.dat -

• myproject/
  • dune
  • myprogram.ml
  • mydata.dat

I have a dune file -

(executable
 (name myprogram))

When I run the program -

$ dune build myprogram.exe
$ cd _build/default
$ ./myprogram.exe

Fatal error: exception Sys_error("./mydata.dat: No such file or directory")

I tried adding a rule -

(rule
 (targets "./mydata.dat")
 (action (copy "./mydata.dat" "./mydata.dat")))

But obviously I'm doing it wrong -

$ dune build myprogram.exe

Error: Multiple rules generated for _build/default/mydata.dat:
- file present in source tree
- dune:4
Hint: rm -f mydata.dat

How can I have dune include mydata.dat in my projects build so myprogram.exe always has access to it?

Answer 1

Just replace ./mydata.dat with mydata.dat in myprogram.ml .