# Having a julia package inside a monorepo called from python

**URL:** <https://discourse.julialang.org/t/having-a-julia-package-inside-a-monorepo-called-from-python/132549>\
**Category:** General Usage\
**Tags:** python, ffi, pythoncalljl\
**Created:** [September 22, 2025, 1:37am UTC](https://discourse.julialang.org/t/having-a-julia-package-inside-a-monorepo-called-from-python/132549 "2025-09-22T01:37:53Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![oxinabox](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/oxinabox/32/206603_2.png) [@oxinabox](https://discourse.julialang.org/u/oxinabox)\
**Post date:** [September 22, 2025, 1:37am UTC](https://discourse.julialang.org/t/having-a-julia-package-inside-a-monorepo-called-from-python/132549/1 "2025-09-22T01:37:53Z")

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so I have a largish python code base in a nice mono-repo.  
(Its also got some typescript in there).

I want to move some of our core logic to julia for performanced.

So I thought I would make a (local, unregistered) julia package inside the mono repo.  
and then uses JuliaCall (PythonCall) to call it from python.  
And it in turn would load whatever packages it needs.

However, I seem to be running in to no end of trouble with getting things to instantiate etc.

It seems like the more well trodden path is to use some registered 3rd party julia package from python.  
But i do not want that, I want to write and develop the julia code along side the python code.

is my workflow sillly?  
Does anyone have a working setup for this?

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<div class="post-metadata">

**Author:** ![oxinabox](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/oxinabox/32/206603_2.png) [@oxinabox](https://discourse.julialang.org/u/oxinabox)\
**Post date:** [September 22, 2025, 3:26am UTC](https://discourse.julialang.org/t/having-a-julia-package-inside-a-monorepo-called-from-python/132549/2 "2025-09-22T03:26:55Z")

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I think it is this:

Create your local package at `Monorepo/foo/Bar`.  
With it’s Project.toml at `Monorepo/foo/Bar/Project.toml`  
which must contain a name `Bar` and a UUID like `dea5d25c-9d64-4551-98ce-2df8e018f89c`  
and it’s Manifest.toml at `Monorepo/foo/Bar/Manifest.toml`  
and it’s source code at `Monorepo/foo/Bar/src/Bar.jl`

then:

```python
import juliapkg
juliapkg.add(
    "Bar",
    "dea5d25c-9d64-4551-98ce-2df8e018f89c",
     path="Monorepo/foo/Bar"),
    dev=True
)
juliapkg.resolve()

```

and do **not** touch `JULIA_LOAD_PATH`.  
and do **not** set `PYTHON_JULIAPKG_PROJECT` or `PYTHON_JULIACALL_PROJECT` to `Monorepo/foo/Bar`  
(but potentiallly do set it to `Monorepo/julia_env`)

Then `Bar` is a normal julia package that you have locally.  
And you have installed it (dev’d it) into the enviroment for the python project