4 ms·
If I'm not mistaken, considering the category of subtyping relationship you get exactly that: with the covariant functor you get (in Scala notation) if B <: A t
by gclaramunt 11y ago
If I'm not mistaken, considering the category of subtyping relationship you get exactly that: with the covariant functor you get (in Scala notation) if B <: A then F[B] <: F[A] and with the contravariant functor if B <: A then F[B] >: F[A]
('<:' means subtype and '>:' supertype )