α : Type u_2
β : Type u_1
γ : Type ?u.274085
p : α → Prop
inst✝ : DecidablePred p
f : β → α
s : Multiset β
l : List β
⊢ List.map f (List.filter ((fun b => decide (p b)) ∘ f) l) ~ List.map f (List.filter (fun b => decide (p (f b))) l)
α : Type u_2
β : Type u_1
γ : Type ?u.274085
p : α → Prop
inst✝ : DecidablePred p
f : β → α
s : Multiset β
l : List β
⊢ filter p (map f (Quot.mk Setoid.r l)) = map f (filter (p ∘ f) (Quot.mk Setoid.r l))
simp [List.map_filter]
no goals
α : Type u_2
β : Type u_1
γ : Type ?u.274085
p : α → Prop
inst✝ : DecidablePred p
f : β → α
s : Multiset β
l : List β
⊢ List.map f (List.filter ((fun b => decide (p b)) ∘ f) l) ~ List.map f (List.filter (fun b => decide (p (f b))) l)
rfl