Desugar tuples to records

[rtfeldman]

This is part of the SIMD proposal, and comes after https://github.com/rtfeldman/roc/issues/2932 and https://github.com/rtfeldman/roc/issues/2934

Tuples should desugar to numbered record fields; e.g. (a, b) should desugar to { 0: a, 1: b }.

This should presumably be done at the type-checking stage so that we can record that something originated as a tuple, allowing us to pretty-print errors using tuple syntax instead of record syntax even after the desugaring has happened.

[jaredramirez]

Is the desugared version meant to be usable outside of transforming tuples? Meaning, is the following valid Roc?

rec = { a: "hello", 4: 5 }

If the above is valid, we hit a problem destructuring. From the above example

{ 5 } = rec

Here, 5 would be a variable reference & a number literal.

[rtfeldman]

Yeah, the first code snippet should be valid Roc!

{ 5 } = rec should be a new compile error (probably checked during canonicalization) which is that you can't destructure numbered record fields.

[lukewilliamboswell]

Closing as I think this is completed.