It's interesting because when I read about how Rust can rewrite iterators code into more performant direct loops I thought about Joe's blog posts that mentioned the same efforts for .NET. Also Span<T>. It seems .NET will have similar abstractions like Rust (of course not all can be migrated).

LuaJIT does the same, down to an absurd level.

From the luafun library readme (which uses iterators under the hood):

https://github.com/luafun/luafun

————

> Let's see an example:

    > -- Functional style
    > require "fun" ()
    > -- calculate sum(x for x^2 in 1..n)
    > n = 100
    > print(reduce(operator.add, 0, map(function(x) return x^2 end, range(n))))
    328350

    > -- Object-oriented style
    > local fun = require "fun"
    > -- calculate sum(x for x^2 in 1..n)
    > print(fun.range(n):map(function(x) return x^2 end):reduce(operator.add, 0))
    328350

> Lua Fun takes full advantage of the innovative tracing JIT compiler to achieve transcendental performance on nested functional expressions. Functional compositions and high-order functions can be translated into efficient machine code. Can you believe it? Just try to run the example above with `luajit -jdump` and see what happens:

    -- skip some initilization code --
    ->LOOP:
    0bcaffd0  movaps xmm5, xmm7
    0bcaffd3  movaps xmm7, xmm1
    0bcaffd6  addsd xmm7, xmm5
    0bcaffda  ucomisd xmm7, xmm0
    0bcaffde  jnb 0x0bca0024        ->5
    0bcaffe4  movaps xmm5, xmm7
    0bcaffe7  mulsd xmm5, xmm5
    0bcaffeb  addsd xmm6, xmm5
    0bcaffef  jmp 0x0bcaffd0        ->LOOP
    ---- TRACE 1 stop -> loop

> The functional chain above was translated by LuaJIT to (!) one machine loop containing just 10 CPU assembly instructions without CALL.