Array (Lean.Compiler.LCNF.Param Lean.Compiler.LCNF.Purity.pure) →
  Lean.Compiler.LCNF.Code Lean.Compiler.LCNF.Purity.pure →
    optParam Lean.Name `_f → Lean.Compiler.LCNF.CompilerM (Lean.Compiler.LCNF.FunDecl Lean.Compiler.LCNF.Purity.pure)