Package ocaml-variants

Failed to find a solution:

no platform:
2024-04-09 20:44.08 [INFO] Solving for ocaml-base-compiler, ocaml,
                           ocaml-variants using opam_repository_commit c06ca4cbc3cf018c28913b4b1a16b89909c3a9f3

2024-04-09 20:45.20 [INFO] base: eliminated all possibilities in 1.04 s

2024-04-09 20:45.20 [INFO] = base =

2024-04-09 20:45.20 [INFO] Can't find all required versions.
Selected: base-bigarray.base base-domains.base base-effects.base
          base-nnp.base base-threads.base base-unix.base
          ocaml-variants&ocaml&ocaml-base-compiler ocaml base-domains
- ocaml -> (problem)
    User requested <= 5.1.0
    base-effects base requires >= 4.12.0
    ocaml-variants 5.1.1+effect-syntax requires = 5.1.1
    Rejected candidates:
      ocaml.5.1.0: Incompatible with restriction: = 5.1.1
      ocaml.5.0.1: Incompatible with restriction: = 5.1.1
      ocaml.5.0.0: Incompatible with restriction: = 5.1.1
      ocaml.4.14.3: Incompatible with restriction: = 5.1.1
      ocaml.4.14.2: Incompatible with restriction: = 5.1.1
      ...
- ocaml-base-compiler -> (problem)
    User requested >= 4.04.1
    Rejected candidates:
      ocaml-base-compiler.5.2.0~beta1: In same conflict class (ocaml-core-compiler) as ocaml-variants
      ocaml-base-compiler.5.2.0~alpha1: In same conflict class (ocaml-core-compiler) as ocaml-variants
      ocaml-base-compiler.5.1.1: In same conflict class (ocaml-core-compiler) as ocaml-variants
      ocaml-base-compiler.5.1.1~rc1: In same conflict class (ocaml-core-compiler) as ocaml-variants
      ocaml-base-compiler.5.1.0: In same conflict class (ocaml-core-compiler) as ocaml-variants
      ...
- ocaml-variants -> ocaml-variants.5.1.1+effect-syntax
    User requested = 5.1.1+effect-syntax