Theorem: Option.map_isSome (Etch/Verification/Misc.lean)

State before:
m : Type u → Type v
inst✝ : Monad m
α β : Type u_1
x : Option α
y : α → β
⊢ isSome (y <$> x) = isSome x
Tactic:
cases x <;> simp
State after:
no goals