add method for installing bash completions from optparse-applicative

[cdepillabout]

It would be nice to have an easy way of installing bash completions from optparse-applicative.

We've added a small post install script to our own CLI tools with a module like the following:

{pkgs, ...}:
{
    packages.our-pkg-one.components.exes.our-exe-one.build-tools = [ pkgs.installShellFiles ];
    packages.our-pkg-one.components.all.postInstall = pkgs.lib.mkForce "";
    packages.our-pkg-one.components.exes.our-exe-one.postInstall = ''
      $out/bin/our-exe-one --bash-completion-script $out/bin/our-exe-one > our-exe-one.bash
      installShellCompletion --name our-exe-one --bash our-exe-one.bash
    '';

    packages.our-pkg-two.components.exes.our-exe-two.build-tools = [ pkgs.installShellFiles ];
    packages.our-pkg-two.components.all.postInstall = pkgs.lib.mkForce "";
    packages.our-pkg-two.components.exes.our-exe-two.postInstall = ''
      $out/bin/our-exe-two --bash-completion-script $out/bin/our-exe-two > our-exe-two.bash
      installShellCompletion --name our-exe-two --bash our-exe-two.bash
    '';

However, this is somewhat repetitive. It would be ideal if haskell.nix provided some sort of functionality for easily enabling this for a given package/exe.

---

The haskell stuff in nixpkgs has a function for doing this:

https://github.com/NixOS/nixpkgs/blob/9dacdec2d9757dd3f2daa68f8760a543581b609a/pkgs/development/haskell-modules/lib.nix#L369-L414

[NorfairKing]

See #624, +1

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[ryantrinkle]

I don't know how to turn this into a PR for haskell.nix, but here is a way to achieve this:

let
  postInstallGenerateOptparseApplicativeCompletion = exeName: ''
    bashCompDir="''${!outputBin}/share/bash-completion/completions"
    zshCompDir="''${!outputBin}/share/zsh/vendor-completions"
    fishCompDir="''${!outputBin}/share/fish/vendor_completions.d"
    mkdir -p "$bashCompDir" "$zshCompDir" "$fishCompDir"
    "''${!outputBin}/bin/${exeName}" --bash-completion-script "''${!outputBin}/bin/${exeName}" >"$bashCompDir/${exeName}"
    "''${!outputBin}/bin/${exeName}" --zsh-completion-script "''${!outputBin}/bin/${exeName}" >"$zshCompDir/_${exeName}"
    "''${!outputBin}/bin/${exeName}" --fish-completion-script "''${!outputBin}/bin/${exeName}" >"$fishCompDir/${exeName}.fish"
    # Sanity check
    grep -F ${exeName} <$bashCompDir/${exeName} >/dev/null || {
      echo 'Could not find ${exeName} in completion script.'
      exit 1
    }
  '';
  project = pkgs.haskell-nix.project {
    src = ...;
    compiler-nix-name = ...;
    modules = [
      ({...}: {
        packages.nix-thunk.components.exes.nix-thunk.postInstall = postInstallGenerateOptparseApplicativeCompletion "nix-thunk";
      })
    ];
  };
in ...

The shell script is directly out of nixpkgs' generateOptparseApplicativeCompletions.

@NorfairKing @cdepillabout @disassembler