Package base-effects

Failed to find a solution:

no platform:
2024-02-20 18:22.11 [INFO] Solving for ocaml-base-compiler, ocaml,
                           base-effects using opam_repository_commit c55e2f61591f0731aea1cb23bfd4b675c54b5ab2

2024-02-20 18:23.08 [INFO] base: eliminated all possibilities in 1.20 s

2024-02-20 18:23.08 [INFO] = base =

2024-02-20 18:23.08 [INFO] Can't find all required versions.
Selected: base-bigarray.base base-domains.base base-nnp.base
          base-threads.base base-unix.base ocaml-config.3
          ocaml-options-vanilla.1 base-effects&ocaml&ocaml-base-compiler
          ocaml-base-compiler ocaml-base-compiler ocaml base-domains
          ocaml-base-compiler
- base-effects -> base-effects.base
    User requested = base
- ocaml -> ocaml.5.1.0
    User requested <= 5.1.0
- ocaml-base-compiler -> ocaml-base-compiler.5.1.0
    User requested >= 4.04.1
    ocaml-base-compiler|ocaml-variants|ocaml-system|dkml-base-compiler ocaml-base-compiler requires >= 5.1.0~ & < 5.1.1~
- ocaml-variants -> (problem)
    Rejected candidates:
      ocaml-variants.5.3.0+trunk: In same conflict class (ocaml-core-compiler) as ocaml-base-compiler
      ocaml-variants.5.2.0+trunk: In same conflict class (ocaml-core-compiler) as ocaml-base-compiler
      ocaml-variants.5.2.0~alpha1+options: In same conflict class (ocaml-core-compiler) as ocaml-base-compiler
      ocaml-variants.5.1.2+trunk: In same conflict class (ocaml-core-compiler) as ocaml-base-compiler
      ocaml-variants.5.1.1+tsan: In same conflict class (ocaml-core-compiler) as ocaml-base-compiler
      ...