prettyPreExp pp lvl alvl wrap (IndexCons t h)
  = wrap $
      text "index" <+>
      parens (prettyPreExp pp lvl alvl parens t <+> text ":." <+> prettyPreExp pp lvl alvl parens h)
prettyPreExp pp lvl alvl wrap (IndexCons t h)
  = wrap $
      text "index" <+>
      parens (prettyPreExp pp lvl alvl parens t <+> text ":." <+> prettyPreExp pp lvl alvl parens h)
prettyPreExp pp lvl alvl wrap (IndexCons t h)
  = wrap $
      text "index" <+>
      parens (prettyPreExp pp lvl alvl parens t <+> text ":." <+> prettyPreExp pp lvl alvl parens h)