earley-ocaml 1.0.1

Error log

The package failed to build. The error log from opam follows.

Opam plugin "depext" may require upgrading/reinstalling. Reinstall the plugin on the current switch? [Y/n] y
The following actions will be performed:
  - recompile opam-depext 1.2.3

<><> Processing actions <><><><><><><><><><><><><><><><><><><><><><><><><><><><>
-> retrieved opam-depext.1.2.3  (cached)
-> removed   opam-depext.1.2.3
-> installed opam-depext.1.2.3
Done.

<><> opam-depext.1.2.3 installed successfully <><><><><><><><><><><><><><><><><>
=> opam-depext is unnecessary when used with opam >= 2.1. Please use opam install directly instead
# Run eval $(opam env) to update the current shell environment

<><> Carrying on to "opam depext -viy earley-ocaml.1.0.1 ocamlfind.1.9.6 ocamlbuild.0.14.3 earley.1.0.1" 

Since version 2.1, opam now handles external dependencies alongside OCaml ones, and the `depext` plugin interface is provided for backwards compatibility only. Consider using your usual `opam install` command to install both OCaml and system dependencies, or `opam install <pkg> --depext-only` if you want to only install external dependencies.
# Detecting depexts using vars: arch=x86_64, os=linux, os-distribution=debian, os-family=debian
[ERROR] No solution for earley-ocaml.1.0.1 & ocamlfind.1.9.6 & ocamlbuild.0.14.3 & earley.1.0.1:   * No agreement on the version of ocaml:
            - (invariant) -> ocaml-base-compiler = 4.06.1 -> ocaml = 4.06.1
            - earley-ocaml = 1.0.1 -> ocaml < 4.06.1
            You can temporarily relax the switch invariant with `--update-invariant'
          * Missing dependency:
            - earley-ocaml = 1.0.1 -> ocaml < 4.06.1 -> ocaml-base-compiler < 3.07+1 | ocaml-system < 3.07+1 | ocaml-variants < 3.8~
            not available because the package is pinned to version 4.06.1
            unmet availability conditions: 'sys-ocaml-version = "3.07"'
            no matching version
          * Missing dependency:
            - earley-ocaml = 1.0.1 -> ocaml < 4.06.1 -> ocaml-base-compiler = 3.07+1 | ocaml-system = 3.07+1 | ocaml-variants < 3.8~
            not available because the package is pinned to version 4.06.1
            unmet availability conditions: 'sys-ocaml-version = "3.07+1"'
            no matching version
          * Missing dependency:
            - earley-ocaml = 1.0.1 -> ocaml < 4.06.1 -> ocaml-base-compiler = 3.07+2 | ocaml-system = 3.07+2 | ocaml-variants < 3.8~
            not available because the package is pinned to version 4.06.1
            unmet availability conditions: 'sys-ocaml-version = "3.07+2"'
            no matching version
          * Missing dependency:
            - earley-ocaml = 1.0.1 -> ocaml < 4.06.1 -> ocaml-base-compiler = 3.08.0 | ocaml-system < 3.08.1~ | ocaml-variants < 3.08.1~
            not available because the package is pinned to version 4.06.1
            unmet availability conditions, e.g. 'sys-ocaml-version = "3.08.0"'
            no matching version
          * Missing dependency:
            - earley-ocaml = 1.0.1 -> ocaml < 4.06.1 -> ocaml-base-compiler = 3.08.1 | ocaml-system < 3.08.2~ | ocaml-variants < 3.08.2~
            not available because the package is pinned to version 4.06.1
            unmet availability conditions, e.g. 'sys-ocaml-version = "3.08.1"'
            no matching version
          * Missing dependency:
            - earley-ocaml = 1.0.1 -> ocaml < 4.06.1 -> ocaml-base-compiler = 3.08.2 | ocaml-system < 3.08.3~ | ocaml-variants < 3.08.3~
            not available because the package is pinned to version 4.06.1
            unmet availability conditions, e.g. 'sys-ocaml-version = "3.08.2"'
            no matching version
          * Missing dependency:
            - earley-ocaml = 1.0.1 -> ocaml < 4.06.1 -> ocaml-base-compiler = 3.08.3 | ocaml-system < 3.08.4~ | ocaml-variants < 3.08.4~
            not available because the package is pinned to version 4.06.1
            unmet availability conditions, e.g. 'sys-ocaml-version = "3.08.3"'
            no matching version
          * Missing dependency:
            - earley-ocaml = 1.0.1 -> ocaml < 4.06.1 -> ocaml-base-compiler = 3.08.4 | ocaml-system < 3.08.5~ | ocaml-variants < 3.08.5~
            not available because the package is pinned to version 4.06.1
            unmet availability conditions, e.g. 'sys-ocaml-version = "3.08.4"'
            no matching version
          * Missing dependency:
            - earley-ocaml = 1.0.1 -> ocaml < 4.06.1 -> ocaml-base-compiler = 3.09.0 | ocaml-system < 3.09.1~ | ocaml-variants < 3.09.1~
            not available because the package is pinned to version 4.06.1
            unmet availability conditions, e.g. 'sys-ocaml-version = "3.09.0"'
            no matching version


Command failed: opam --cli=2.1 list --readonly --external '--resolve=earley-ocaml.1.0.1,ocamlfind.1.9.6,ocamlbuild.0.14.3,earley.1.0.1' --color=never returned 20