I'm unable to use pprint library using melange.

[tonyfettes]

Hi, I'm building a simple single-stepper for a small ocaml-like programming language at https://github.com/tonyfettes/stepper

It use melange to compile OCaml & reason code to JS and using ReasonReact with Preact.

However, I'm unable to use PPrint as a dependencies to pretty-printing the AST (located at lib/syntax.ml), and it reported an error looks like this:

$ esy dune build
File "/Users/tonyfettes/.esy/3_______________________________________________________________/i/opam__s__pprint-opam__c__20230830-b72f018f/lib/pprint/dune-package", line 26, characters 0-521:
26 | (library
27 |  (name pprint)
28 |  (kind normal)
....
43 |      (path PPrintEngine)
44 |      (intf (path PPrintEngine.mli))
45 |      (impl (path PPrintEngine.ml)))))))
Error: File unavailable:
/Users/tonyfettes/.esy/3_______________________________________________________________/i/opam__s__pprint-opam__c__20230830-b72f018f/lib/pprint/melange/pPrint.cmj
-> required by _build/default/web/output/node_modules/pprint/PPrint.js
-> required by alias web/all
-> required by alias default
File "/Users/tonyfettes/.esy/3_______________________________________________________________/i/opam__s__pprint-opam__c__20230830-b72f018f/lib/pprint/dune-package", line 26, characters 0-521:
26 | (library
27 |  (name pprint)
28 |  (kind normal)
....
43 |      (path PPrintEngine)
44 |      (intf (path PPrintEngine.mli))
45 |      (impl (path PPrintEngine.ml)))))))
Error: File unavailable:
/Users/tonyfettes/.esy/3_______________________________________________________________/i/opam__s__pprint-opam__c__20230830-b72f018f/lib/pprint/melange/pPrintEngine.cmj
-> required by _build/default/web/output/node_modules/pprint/PPrintEngine.js
-> required by alias web/all
-> required by alias default

I don't know which is a better repository to report (the pprint one or this one), so I just choose to post it here.

Is there anyway I can approach to this issue?

Thanks in advance!

Steps to reproduce

# clone my repo
git clone http://github.com/tonyfettes/stepper.git stepper
cd stepper
# checkout the reproduce branch
git switch melange-pprint-reproduce
# install esy
esy install
esy
esy dune build

[tonyfettes]

After some digging and reading dune's document on melange here, I believe this is not possible without modifying the pprint library or vendor it in my source repository. I'll leave this open for some days to see if I or anyone can have better ideas on how to deal with it.