It's 2025, can we have a “lazy let”?

[ksluder (Kyle Sluder)]

@Slava_Pestov

At the implementation level, we could make ‘lazy let’ work easily enough; it would still desugar to a computed property with a mutable getter, and it would continue to behave as one, so nothing would violate the law of exclusivity.

I view the Law of Exclusivity as encompassing more than just the prohibition of more than one simultaneous exclusive access, but also what you are allowed to do with exclusive or non-exclusive accesses. Perhaps those are officially separate rules or corollaries.

Either way, it was originally not permissible to call a mutating method via non-exclusive access. (Methods on classes are never mutating.) That changed with the introduction of atomics. Permitting lazy let would require changing it yet again.