Hey @adrinjalali, you shouldn't need to change anything in the meson.build files. I recently did a full update of the build docs, and https://numpy.org/devdocs/building/index.html should be up to date.

Simplest way to get started:

mamba env create -f environment.yml 
mamba activate numpy-dev
spin build  # or `spin test`

If you're having a specific problem or running into a build error, can you add more details about what you did and are seeing?

I'll assume this was a simple misunderstanding, and close this. If not, please comment again @adrinjalali and we'll reopen.

So the issue is that I was adding cython files in a separate folder to isolate that part of the code, which means I would need to add a new meson.build file. I did, and I figured that out after trying different things (wasn't easy since I didn't know much about how meson works).

Then then issue is still that I don't know how to make it understand where the numpy import directory is. In other projects they all use the same code to get the import folder, but I'm having a hard time understanding how that works in numpy itself.

Ah okay, that clears up what you were trying to do.

Then then issue is still that I don't know how to make it understand where the numpy import directory is.

All you need to do is add np_dep (or, if this is within numpy itself, np_core_dep) as a dependency to your new py.extension_module() call in the new meson.build file. You can simply copy-paste the way current Cython extensions are built I think (e.g., numpy/random/meson.build has some).

Feel free to point me to your branch if you need a hand.