law maybe_default_map

bend-mathlib@0.8.1.0 · maybe.bend:145

import Base

145# The default of a map, with the mapped default, is the mapped default of the original.
146law maybe_default_map:
147  for ~A: Data
148  for ~B: Data
149  for ~f: A -> B
150  for m: Maybe<&2, A>
151  for -d: A
152  {Maybe.default(&2, B, Maybe.map(&2, A, B, f, m), f(d)) == f(Maybe.default(&2, A, m, d)) : B}