law maybe_is_none_map

bend-mathlib@0.8.1.0 · maybe.bend:130

import Base

130# Mapping keeps whether a value is absent.
131law maybe_is_none_map:
132  for ~A: Data
133  for ~B: Data
134  for ~f: A -> B
135  for m: Maybe<&2, A>
136  {Maybe.is_none(&2, B, Maybe.map(&2, A, B, f, m)) == Maybe.is_none(&2, A, m) : Bool}