Usage:

→ cargo build
   Compiling adder v0.1.0 (/Users/joe/src/adder)
    Finished dev [unoptimized + debuginfo] target(s) in 0.94s
→ cargo run -- test/add.snek  test/add.s
    Finished dev [unoptimized + debuginfo] target(s) in 0.05s
     Running `target/x86_64-apple-darwin/debug/adder test/add.snek test/add.s`
Generated assembly:

section .text
global our_code_starts_here
our_code_starts_here:
  mov RAX, DWORD 73
add RAX, DWORD 1
sub RAX, DWORD 1
sub RAX, DWORD 1
  ret

Evaluates to:
72

Note that main does three different things for output:

1. It creates the .s file as usual
2. It prints out the assembly string
3. It converts the instructions to assembly directly, and evaluates the code

This shows some basics of how to use dynasm to generate code and invoke it from the compiler.