Grammar doesn't allow nesting of conditionals through second argument

[verytactical]

Are you using the latest released (or pre-released, a.k.a. "next") version?

• I'm using the latest Tact version

Tact source code

const a: Int = 2;
const counter: Int = a == 0 ? a == 1 ? a : a : a;

Relevant Tact/build system log output

Parse error: expected ":", ".", "!!", "-", "+", "%", "/", "*", "<=", "<", ">=", ">", ">>", "<<", "&", "==", "!=", "|", "^", "||", or "&&" 
 
Line 2, col 38: 
  1 | const a: Int = 2; 
> 2 | const counter: Int = a == 0 ? a == 1 ? a : a : a; 
                                           ^

What happened?

Grammar disallows nesting conditionals through second argument

What did you expect?

Grammar allows nesting conditionals through second argument, as in pretty much any other C-like language

Steps to reproduce

No response

How do you run Tact?

Other

Anything else?

No response

[anton-trunov]

A summary of our discussion elsewhere:

We should forbid a == 0 ? a == 1 ? a : a : a as it's done now, because this syntax is really hard to read, so we want to be JS-like but not allow everything if it hurts readability. For instance, a / 2 / b should also be forbidden if there are not parentheses.

To do that, we might introduce a separate linter-like pass into the compiler.

There are might be many other cases, so we should turn to existing academic research on common mistakes people make because of confusing syntax and draw from industrial best practices.