I came across existential quantification over values in the Scala Language Specification (3.2.10 Existential Types).

x: y.Inner forSome{val y : Outer}

Does someone have illustrative use cases for it?

T forSome {val x: S} is defined as T forSome { type t <: S with Singleton }. The Singletron trait is mentioned in the Specification (3.2.1 Singleton Types) but I could not find it in the Scaladoc. Where is it defined?

scala types existential-type
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