def mem

bend-mathlib@0.8.1.0 · list.bend:703

import Base

703# Membership in a list, as a reusable proposition.
704def mem(~A: Data, ~eq: A -> A -> Bool, +x: A, xs: List<&2, A>) -> Data:
705  {List.contains(~A, ~eq, xs, x) == True{} : Bool}