Error: Unbound module Fields

[agarwal]

$ cat foo.ml
type t = {a:int; b:string} [@@deriving xml]

$ ocamlfind ocamlc -package ppx_xml_conv -c foo.ml
findlib: [WARNING] Interface main.cmi occurs in several directories: ., ~/.opam/4.02.3/lib/ocaml/compiler-libs
File "foo.ml", line 1, characters 0-43:
Error: Unbound module Fields

I checked Fieldslib and it only has Field, not Fields. Many of the ppx_*_conv packages seem to be missing ocamlfind dependencies, e.g. see also janestreet/ppx_sexp_conv#1.

[ghost]

The Fields module comes from [@@deriving fields], from ppx_fields_conv. However I think ppx_xml_conv suffers from the same problem as ppx_csv_conv: janestreet/ppx_csv_conv#1, i.e. the runtime lib for ppx_xml_conv is missing. Sorry for that, we are currently reworking our public release process which will make it easier for us to provide fixes quicker.

[agarwal]

Got it. Thanks.

Just in case anyone else gets to this issue, note there's no manual workaround for now because this lib also ends up depending on the unreleased csvfields mentioned in the other issue.

[vbmithr]

Not working with the ppx-driver method. I think there is 2 issues:

• Impossible to generate the Fields module before the XML code, no matter how I try, I always end up with having the XML code generated before the Fields module.

• When the type has a name, the generated module is Fields_of_name, whereas the generated XML code requires module Fields

[vbmithr]

Ok, actually

type t = {
  a : string ;
} [@@deriving xml,fields]

works, but fails if t has any other name. Still a bug :p

[hhugo]

It seems to be working now and gives better error messages:

type t = {a:int; b:string} [@@deriving xml];;
Error: Deriver fields is needed for xml, you need to add it before in the list