law maybe_map_pure_sym

bend-mathlib@0.8.1.0 · maybe.bend:258

import Base

258# Mapping a pure value is pure of the mapped value, reversed to rewrite toward the simple side.
259law maybe_map_pure_sym:
260  for ~A: Data
261  for ~B: Data
262  for -f: A -> B
263  for -x: A
264  {Maybe.pure(&2, B, f(x)) == Maybe.map(&2, A, B, f, Maybe.pure(&2, A, x)) : Maybe<&2, B>}