[ChrisRackauckas]

You can use CondaPkg.jl (https://github.com/cjdoris/CondaPkg.jl) to setup Python dependencies with version control. I haven't played with it too much but it seemed to work out for what I tried. Indeed the reason why I haven't had too many test cases is because in SciML we removed all Python dependencies since they were the main source of instability. PyDSTool.jl, FEniCS.jl, SymEngine.jl (through ParameterizedFunctions.jl and ModelingToolkit.jl) were the biggest development burdens because of the Python deps changing function names all of the time until they were deprecated and replaced by pure Julia packages, so I definitely know the pain.

[cookieperson]

Is it fair to say that it is your career to rewrite code in Julia to write academic papers about julia?

[ChrisRackauckas]

Most of my time isn't academic or writing code. Most of it is focused on enhancing algorithms to achieve what's required for new methods to work deployed in production environments such as the Pumas clinical pharmacology work, and now working on what's required to get scientific machine learning point-and-click GUI ready. I always leave a little bit of time in mornings and weekends though for some coding, and a little bit a day goes a long way after years.

I stay away from code rewrites like the plague, which is why SciML maintains so many wrapper packages. It's less work and if there's nothing new then rewriting is thankless work. Unless we have some kind of angle for something new in the algorithm, we just recommend someone use the same old wrappers (for instance, IDA with fully-implicit DAEs). We won't beat the C/Fortran code without something new. However in most areas there's lots of interesting research to be done. I could "sabbatical as an academic" and spend the next 3 years just improving explicit Runge-Kutta methods: those for example are probably still 4x away or so from what I think is theoretically possible, but that's not going to happen any time soon since we have some real applications to focus on.

Those package deprecations mentioned above were deprecated by community efforts (BifurcationKit.jl replaced PyDSTool wrappers and was done by Romain Veltz, FEniCS wrappers were largely replaced by Gridap, and SymEngine was replaced by Symbolics which is largely the work of one of the Julia Lab PhD students Shashi). Even those had a largely new element to them though, with BifurcationKit focusing a lot on recent algorithms that other bifurcation software don't have (like the deflated Newton methods), and Shashi's Symbolics.jl work focusing on generality of term rewriting systems to allow for alternative algebras.

[cookieperson]

Think you've dodged the point entirely by fixating on a word rather then the sentiment. Isn't it in your professional interest to endlessly promote Julia at all costs. To find tools in other languages and make sure they are available in Julia, etc?

That's basically my point. Readers should be aware of who is making suggestions and why they might be making them. You have a clear status and financial drivers to say "only use Julia, it's ready for anything, it's fine" while not saying any of the flaws other then "it's fixed if you compile the branch of the grad student I asked to fix it's PR".

Also the type of work you do is incredibly rare. Most people considering trying to use Julia for their day job don't have the resources you have nor the needs or desires you have. In most cases getting one of the most foremost scientific computing in Julia experts take on what tools they should use really doesn't map well to practical users.