Proc pat (L _ (HsCmdTop cmd _ _ _)))
  = hsep [text "proc", ppr pat, ptext (sLit "->"), ppr cmd]

ppr_expr (
ppr_expr (HsProc pat (L _ (HsCmdTop cmd _ _ _)))
  = hsep [text "proc", ppr pat, ptext (sLit "->"), ppr cmd]
ppr_expr (HsProc pat (L _ (HsCmdTop cmd _ _ _)))
  = hsep [text "proc", ppr pat, ptext (sLit "->"), ppr cmd]