Maps require that their keys are comparable for equality at runtime, and any includes values that aren’t. The comparable type captures exactly this constraint, so you should be able to use it as the key of a map: e.g. Map : [comparable]int.
From your example, it looks like you’re trying to use any for values in a map, not the keys. That is allowed, but because any isn’t even comparable, there’s very little you can do with those values. Using comparable for the value would be slightly more useful, but we don’t yet support dynamic downcasting from it.
See also: Is `false` a bottom type in Verse? - #4 by AndrewScheidecker