Existentials and custom constraints

[Lantua]

@AnuzaMaxima

• What is the best way to declare variable with multiple constraints on storable value ?

This is somewhat pitched before, though not as generic existential in Allow for Compile-Time Checked Intervals for Parameters Expecting Literal Values (and other threads in the first few replies).

@AnuzaMaxima

• Will swift acquire any rich functionality, if it posses Any split as shown?

I don't immediately see any benefit. The only demonstration in the pitch is this line.

@AnuzaMaxima

extension AnyNominal { func isConforming(to protocol: Protocol.Type) -> Bool {...} }
"String".isConforming(to: Equatable.self) //true

It doesn't get better since the problem lies in Equatable, not String.
Otherwise, on homogenous protocol you can already do

"String" is SomeHomogenousProtocol

@AnuzaMaxima

• Given all those points , I wonder, whether it would be better to implement opaque storage at language level.

What do you want the opaque storage to be able to do more than Any?