cases (env.get name τ) <;> rfl
α σ : Type
ε : σ → Type
Δ : Dialect α σ ε
τ : MLIRType Δ
name : SSAVal
env : SSAEnv Δ
⊢ (match SSAEnv.get name τ env with
      | some v => fun s => Except.ok (v, s)
      | none => fun s => Except.ok (default, s))
      env =
    Except.ok
      (match SSAEnv.get name τ env with
        | some v => v
        | none => default,
        env)
no goals