Is there any interface between Julia and Wolfram Engine?
There seems to be this one:
You can see a hint of one in Stephen Wolfram’s talk:
If you want to call Julia from Mathematica, look at this:
Actually I want to use Julia to write a front end of the free Wolfram Engine, but couldn’t find any documentation on that …
MathLink.jl is what you need. If you want to write a GUI frontend, you’ll also need a GUI toolkit like GTK.jl or Mousetrap.jl.
But there’s already a free Jupyter notebook kernel frontend for the Wolfram Engine: