Note: Resolution is largely vibes-based, but I'll discuss with traders before resolving.

Occasionally, a feature well-known in the programming language literature will jump over into mainstream languages: lambdas, linear types, typeclasses, sum types and continuation-passing all come to mind as recent-ish examples.

I will resolve one option to YES if at some point a mainstream language implements the listed feature and it sees usage, or if a language with this feature gains mainstream appeal.

I will resolve multiple options to equal percentages if, best I can tell, this happens to multiple of them at the same time.

I will resolve to NA options that I can't judge or that seem too minor to be worth tracking.

For judging "mainstreamness", I'll go by the StackOverflow Yearly Developer Survey (professional), with a cut-off at around 5%.

Judging "sees usage" is harder; I'll decide that on a case-by-case basis. Same with features that amount to the same thing being introduced under a different name.

I'll extend the close date if necessary.