Identified Type-Checking

When a value is assigned to an identified type ascribed concrete member, then this value is type-checked against the type of the member before performing the actual assignement.

More formally, given the identified type ascription I of a concrete member m and a value v that satisfies a type T, if either:

• T is a structural type and T is a structural subtype of I
• T is an identified type and T is an identified subtype of I

then v can be assigned to m.

Note

If the type-check of v against the identified type I succeeds, then v is said to satisfy I.