law maybe_default_map_sym

bend-mathlib@0.8.1.0 · maybe.bend:334

import Base

334# The default of a map, with the mapped default, is the mapped default of the original, reversed to rewrite toward the simple side.
335law maybe_default_map_sym:
336  for ~A: Data
337  for ~B: Data
338  for ~f: A -> B
339  for m: Maybe<&2, A>
340  for -d: A
341  {f(Maybe.default(&2, A, m, d)) == Maybe.default(&2, B, Maybe.map(&2, A, B, f, m), f(d)) : B}