Visibility of derivers

I have an OCaml project built with dune. The preprocessing libraries include ppx_bin_prot.

To debug an issue I’m having, I wanted to see what derivers are installed. I tried getting that information in two ways:

Ppx_derivers.derivers ()


Ppx_deriving.derivers ()

The deriver for bin_io appears in the first list, but not in the second list. In fact, I want the deriver of type Ppx_deriving.deriver so that I can get at one of its fields.

Why does the deriver not appear in the second list? How does dune register the deriver?