law maybe_is_some_map_sym

bend-mathlib@0.8.1.0 · maybe.bend:312

import Base

312# Mapping keeps whether a value is present, reversed to rewrite toward the simple side.
313law maybe_is_some_map_sym:
314  for ~A: Data
315  for ~B: Data
316  for ~f: A -> B
317  for m: Maybe<&2, A>
318  {Maybe.is_some(&2, A, m) == Maybe.is_some(&2, B, Maybe.map(&2, A, B, f, m)) : Bool}