α : Type u_1
M : Type u_2
inst✝¹ : Zero M
inst✝ : DecidableEq α
l : AList fun _x => M
a : α
⊢ Option.getD (lookup a l) 0 = 0 ↔ lookup a l = none ∨ 0 ∈ lookup a l
α : Type u_1
M : Type u_2
inst✝¹ : Zero M
inst✝ : DecidableEq α
l : AList fun _x => M
a : α
⊢ ↑(lookupFinsupp l) a = 0 ↔ ¬a ∈ l ∨ 0 ∈ lookup a l
rw [lookupFinsupp_apply, ← lookup_eq_none]
no goals
α : Type u_1
M : Type u_2
inst✝¹ : Zero M
inst✝ : DecidableEq α
l : AList fun _x => M
a : α
⊢ Option.getD (lookup a l) 0 = 0 ↔ lookup a l = none ∨ 0 ∈ lookup a l
cases' lookup a l with m <;> simp