Just tried it online¹ to see how it deals with a long standing problem² I have with Lua and I'm pleased to see actual improvement in the form of a warning:

    script.pluto:1: warning: function was hinted to return string
    but actually returns nil [type-mismatch]
        1 | function foo(x: number): string 
          | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ here

Unfortunately the underlying table was corrupted when the code ran and only

    1 foo

was generated in the output. I would have preferred it to have refused to run at all (will need to look in the docs to see if there's a way to get that behavior with configuration). The purist in me wants more but the practical side of me appreciates that this is definitely an improvement over current Lua.

¹: https://pluto-lang.org/web/#code=function%20foo(x%3A%20numbe...

²: https://news.ycombinator.com/item?id=38030778