ts-style ignore or any for flexibility

[hunterloftis]

I've just completed converting several thousand lines of lua to teal for two projects. I'm having to revert that change in one project, though, because teal has no mechanism to either:

1. ignore lines/files/blocks or
2. treat any as a flexible "could-be-anything", ala TypeScript

This means that using a 3rd-party lua module without teal types is impossible. You can require the module via a *.d.tl hack like:

local primitives: any
return primitives

...but then every single use will error because, unlike TS, Teal treats any as closed, rather than open:

cannot index key 'square' in variable 'primitives' of type <any type>

So unless you're willing to build types for literally everything you pull in, which is often infeasible, there's just no way to have forward progress.

[hishamhm]

Thank you for the feedback. Teal does have the machinery to allow for these, but the UX is still admittedly less-than-ideal.

If the tl compiler compiles an input file with a .lua extension, then all unannotated variables have an internal unknown type that behaves like you described.

I'll keep this issue open, as we need better ways to handle this. I am not sure if exposing the unknown type is the best way, as I don't want these to propagate in .d.tl files and have it be over-used like any is in TypeScript (there's often a better way to describe a type). But perhaps we could support a lax pragma so that we can enter non-strict mode with an annotation like --#pragma lax on, to be used when converting codebases.