bug: Building web server fails

[RossSmyth]

Hello.

I am building with:

• OCaml 5.3.0
• Dune 3.20.2

With the following deps:

• fpath 0.7.3
• ezgzip 0.2.3
• cohttp-lwt-unix 6.2.1
• cmdliner 1.3.0
• lwt 5.9.2
• base64 3.5.2
• z3 4.15.7
• pprint 8e330afe141268e3e8b80a0d6e4918aa01ca14af
• ppx_sexp_conv 0.17.1
• sexplib 0.17.0
• yojson 3.0.0
• lem 2025-03-13
• result 1.5
• ppx_deriving 6.1.1
• zarith 1.14
• menhir 20250903

Then I run:

> make PROFILE="release" cerberus-web

which results in:

 (debug 0): constructValue_aux: is WRONG for union ==> always assigning the first member
 File "backend/web/web.ml", line 499, characters 2-35:
 499 |   Server.respond_string ~flush:true ~headers ~status:`OK ~body ()
         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 Error: The function Server.respond_string has type
          ?headers:Http.Header.t ->
          status:Http.Status.t ->
          body:string ->
          unit -> Cohttp_lwt_unix.Server.response Cohttp_lwt_unix.Server.IO.t
        It is applied to too many arguments
 File "backend/web/web.ml", line 499, characters 31-35:
 499 |   Server.respond_string ~flush:true ~headers ~status:`OK ~body ()
                                      ^^^^
   This extra argument is not expected.
 make: *** [Makefile:118: cerberus-web] Error 1

[kmemarian]

Hello,

We have an upper bound on the version of the cohttp-lwt-unix package (< 6.0.0) as the API has changed.

If you install the dependencies using the following command, opam will fetch the proper versions:

opam install --deps-only ./cerberus-web.opam ./cerberus-lib.opam

I have updated the README with better instructions and you'll also want pull the last commit (e3870d1) as there were other issue when building the typescript of the webapp.

Note that the webapp is not maintained at the moment, so it may not work well.