split <;> simp_all
α : Type
inst✝² : BEq α
inst✝¹ : Hashable α
inst✝ : DecidableEq α
assign : α → Bool
decls1 decls2 : Array (Decl α)
start : Nat
hdag1 : IsDag α decls1
hdag2 : IsDag α decls2
hbounds1 : start < decls1.size
hbounds2 : start < decls2.size
hprefix : IsPrefix decls1 decls2
hidx1 : decls2[start] = decls1[start]
idx✝ : α
heq : decls1[start] = Decl.atom idx✝
⊢ assign idx✝ =
    match elem : decls1[start] with
    | Decl.const b => b
    | Decl.atom v => assign v
    | Decl.gate lhs rhs linv rinv =>
      let_fun this := ⋯;
      let lval := go lhs decls1 assign ⋯ hdag1;
      let rval := go rhs decls1 assign ⋯ hdag1;
      xor lval linv && xor rval rinv
no goals