Ask HN: High performance, inline functions: how in different ecosystems?

Hi there!

I am mostly a TS/JS dev with some advanced python skills and C/C++/Java/C# background from the uni, but not really up to date regarding to low level/high performance options.

I am wondering what options do I have for having really high performance (for my custom algorithms) in different ecosystems with an extra: inline functions. (I mean ecosystems like JVM world, web world, C/CPP world, etc.)

I really like the way inline functions can "compose" and nest in each other and access the parent scopes variables without any troubles.

I have tried to look up Rust/C/C++/Nim/WebAssembly/Static-Typescript/others looking for "modern" solutions/options, but as I am not in these fields it is quite hard to me to evaluate if something (like a weird C macro) would really be robust in that regard.

Could you please give ideas and hows on that in ecosystems you know more about?

So requirements are: 1. High performance 2. Inline functions (3. Any ecosystem)