>>117
Use sage.
This is a great philosophy, but if you really believe it, then the first thing you should do is dump functional programming.
You're talking about
purely functional programming, right? Because in a language that merely emphasizes functional programming, there's nothing stopping you from heavily mutating things all while nicely compartmentalizing computation as you would in functional programming.
immutability and garbage collection across the board, whether it's needed or not
If you can't recognize whether the JIT can optimize away unneeded copies of things (e.g. via escape analysis) and that you should replace them with direct mutation, or you can't tell when the JIT will be unable to choose a type-specific container and you should enforce (or hint) it manually, then you shouldn't be allowed to use a high-level language. As simple as that.
If you really wanted to follow that philosophy to the letter of the law, I don't see how you could be anything but a C programmer.
C, when compiled directly to machine code, will always yield lower performance at the same levels of complexity as a higher level language (kindly resist the temptation of pointing out shitty languages with even shittier implementations as a counterexample to this). A well-written JIT may yield faster code than a static compiler via profiling.
All in all, kindly stop hating on a certain way of doing things simply because some (if not most) of its proponents are cretins.