(ℕ → Lean.Compiler.LCNF.LitValue) →
  Array (Lean.Compiler.LCNF.Arg Lean.Compiler.LCNF.Purity.pure) →
    Lean.Compiler.LCNF.Simp.ConstantFold.FolderM (Option (Lean.Compiler.LCNF.LetValue Lean.Compiler.LCNF.Purity.pure))