Constants as array keys

[jrcii]

A few years ago @muglug stated that (paraphrasing) "array keys can't be indirect" and therefore can't be constants.

If there exists a string used both in code and would-appear-if-possible in various type definitions as keys, how would you DRY that if this isn't possible?

Is there a set/type theory/design reason for this limitation, or, is it just a hard implementation problem either in general or due to Psalm's internal architecture?

[orklah]

Not sure if it was a Parser limitation. I can't think of any other reason. If you can get that to work, I'd merge it :)