In the description we have that

All test cases will be valid programs

but then nowhere we have a description that program is just one function.

I think either adding program ::= function to the grammar, or saying that testcases will be valid functions would save me quite some confusion and probably few minutes.

I've re-written the Rust translation, to address a number of issues:

• Initial training setup no longer uses outdated rust syntax, and compiles cleanly.
• Provides a pre-defined Ast enum, including derive(Debug).
• Provide enums for the binop operations (add, sub, mul, div), and for the value sources (imm or arg)
• It still provides a sample tokenizer (like the other translations) but no longer tests it or requires that it is still there in the solution. Trainees should be able to use alternative approaches.
• The sample tokenizer now shares string slices with the underlying program string slice.
• Ensure that the operator associativity test fails if the solution outputs an empty assembly vector.
• Because the provided enums implement Debug, test error output should be much better.
• No longer tests the provided simulator or if the compiler can be created.

Please approve!

I've created a fork that addresses all of these issues except for the randomised tests, since none of the other translations have randomised tests either.

And another issue:

• The sample tests do nothing. They instead comprise the simulator and a small test for the simulator. 🤦‍♂️

Seemed like the fixed tests either got added or removed some time ago, because I saw all languages have unified fixed test cases now, would have to check and verify it again later ^^

Description can & should be made language agnostic.

Sorry, which testcase is it that should be added?

I'm fixing the Ruby version.

Nice kata, good if you want to learn about closures

Lua translation!

yes it is, here are docs with a great breakdown https://docs.codewars.com/gamification/ranks/

Because the first 9 chars expected to be digits

too many edge cases for this during testing.

great problem!
Would love to see a follow up problem to this one maybe something like getting assembly (or some kind of bytecode) as input and the goal is to produce a readable expression like:
input:
AR 0 SW IM 2 MU SW IM 1 SU
output:
[a] 1-a*2
(this wouldn't be a 1kyu problem but it would be fun :) )

Cool kata! It feels like a real world problem.