personal notes

the most interesting part to me is the virtual machine. basically that means simulate a underlying os. with this ability to customize runtime, it can unlock many potentials.

how a virtual machine is implemented

for a virtual machine to work, it has to

• able to branching, looping, this indicates it must has a conditional jump ability to some code address
• call subroutine, this is done using function frame to booking values at registers or some other medium
• store computation result. in a normal stack based machine, this is stored at regsiters.

lust: Lua in Rust

This project implements a parser, compiler, and virtual machine evaluator for a minimal subset of Lua. It is written from scratch in Rust.

See the companion blog post, Writing a minimal Lua implementation with a virtual machine from scratch in Rust , for a guided walkthrough of the code.

Example

$ cargo build --release
$ cat test/fib.lua
function fib(n)
   if n < 2 then
      return n;
   end

   local n1 = fib(n-1);
   local n2 = fib(n-2);
   return n1 + n2;
end

print(fib(30));
$ time ./target/release/lust test/fib.lua
832040
./target/release/lust test/fib.lua  0.29s user 0.00s system 99% cpu 0.293 total
$ time lua test/fib.lua
832040
lua test/fib.lua  0.06s user 0.00s system 99% cpu 0.063 total

More examples

See the test directory.