# Issue with preprocessing with \`visitors\`

**URL:** <https://discuss.ocaml.org/t/issue-with-preprocessing-with-visitors/331>\
**Category:** Ecosystem\
**Tags:** visitors, jbuilder, build\
**Created:** [June 2, 2017, 9:05am UTC](https://discuss.ocaml.org/t/issue-with-preprocessing-with-visitors/331 "2017-06-02T09:05:10Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![grayswandyr](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.ocaml.org/grayswandyr/32/94_2.png) [@grayswandyr](https://discuss.ocaml.org/u/grayswandyr)\
**Post date:** [June 2, 2017, 9:05am UTC](https://discuss.ocaml.org/t/issue-with-preprocessing-with-visitors/331/1 "2017-06-02T09:05:10Z")

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Hi, anyone knows how to configure the jbuild file to use F. Pottier’s “visitors” PPX?

EDIT: oh right it seems that jbuilder only works with package relying on ocaml-migrate-parsetree, which does not seem to be the case of visitors (nor ppx\_deriving for that matter, if I get it right).