RuntimeConstraint

A RuntimeConstraint is similar to a Constraint with the difference that it can be used in non-inlined methods.

This allows refinement of values in polymorphic methods / givens without the use of inline. e.g., the code below would fail to compile if Constraint was used instead.

def foo[A, C](value: A)(using c: RuntimeConstraint[A, C]): Either[String, A :| C] =
 if c.test(value) then Right(value.assume[C]) else Left(c.message)

In cases that one does not exist in scope, one will be automatically derived from a Constraint.