have := (Primrec.of_equiv_symm (e := equivW L μ)).comp
  ((this.comp (Primrec.const ()) Primrec.id).comp (Primrec.of_equiv (e := equivW L μ)))
L : Language
μ : Type v
inst✝⁴ : (k : ℕ) → Primcodable (L.Func k)
inst✝³ : (k : ℕ) → Primcodable (L.Rel k)
inst✝² : UniformlyPrimcodable L.Func
inst✝¹ : UniformlyPrimcodable L.Rel
inst✝ : Primcodable μ
this : Primrec₂ fun x w => WType.mk ((fun x => (false, Sum.inr (Sum.inr (Sum.inr ())))) x) fun x => w
⊢ Primrec ex
L : Language
μ : Type v
inst✝⁴ : (k : ℕ) → Primcodable (L.Func k)
inst✝³ : (k : ℕ) → Primcodable (L.Rel k)
inst✝² : UniformlyPrimcodable L.Func
inst✝¹ : UniformlyPrimcodable L.Rel
inst✝ : Primcodable μ
this✝ : Primrec₂ fun x w => WType.mk ((fun x => (false, Sum.inr (Sum.inr (Sum.inr ())))) x) fun x => w
this :
  Primrec fun a =>
    (equivW L μ).symm (WType.mk ((fun x => (false, Sum.inr (Sum.inr (Sum.inr ())))) ()) fun x => id ((equivW L μ) a))
⊢ Primrec ex