Than you would probably like the Nim[1] programming language. It has the syntax of python, but transpiles to C/C++. A good type system. The main problem would probably the compiles times. Because you basically compile just C/C++ code. And of course the eco-system is much much smaller than Python.
Nim compile+link times can be sub-100 milliseconds with tcc [1] (just saw 93 ms on my laptop) which can yield pretty reasonable edit-compile-test cycles.
The grandparent's scientific/Go interests suggests a need for a large, working ecosystem and there are probably several places in ArrayMancer which need some love for "fallback cases" to work with tcc (or elsewhere in the as you note much smaller Nim eco-system).
EDIT: E.g., for ArrayMancer you need to make stb_image.h work with tcc by adding a nim.cfg/config.nims `passC="-DSTBIW_NO_SIMD -DSTBI_NO_SIMD"` directive, though. And, of course, to optimize compile times, just generally speaking, you always want to import only exactly what you really need which absolutely takes more time/thought.
[1] https://github.com/TinyCC/tinycc
I agree with this sentiment.
I try to learn the basics of new programming language regularly and write a small lisp alike interpreter in it and give myself a maximum of 2 days working on it. It covers things like string handling, regexp, recursion, lambdas, garbage collection, ... and run them through a tiny test suite.
In Python and JS, it was easy to do it and the code was still very readable. In C++, the language I earn my money from, I had a bug I was not able to fix within the given time frame, happening just with gcc not clang, assuming some undefined behavior. In C, I was able to add my own garbage collector with muss less work than I expected ... but
Nim really impressed me, it really felt almost like I wrote it in Python, but an executable which run on its own and being quite a bit faster.
Working mostly in the embedded world, where ecosystem matters somewhat less. If any employee ever would give me a chance to choose a language myself I would definitely try to write a first prototype in Nim.
I think, Nim is probably the best fit.
It also compiles to JS.