tidyExpr env (Case e b ty alts)
  = tidyBndr env b      =: \ (env', b) ->
    Case (tidyExpr env e) b (tidyType env ty)
         (map (tidyAlt b env') alts)
tidyExpr env (Case e b ty alts)
  = tidyBndr env b      =: \ (env', b) ->
    Case (tidyExpr env e) b (tidyType env ty)
         (map (tidyAlt b env') alts)
tidyExpr env (Case e b ty alts)
  = tidyBndr env b      =: \ (env', b) ->
    Case (tidyExpr env e) b (tidyType env ty)
         (map (tidyAlt b env') alts)