Theorem: Option.map_is_some' (Etch/Verification/Misc.lean)

State before:
m : Type u → Type v
inst✝ : Monad m
α : Type u_1
β : Type u_2
x : Option α
f : α → β
⊢ isSome (Option.map f x) = isSome x
Tactic:
cases x <;> simp
State after:
no goals