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```

     

       
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:::

     

       
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### `mkPackageOption`, `mkPackageOptionMD` {#sec-option-declarations-util-mkPackageOption}

     

       
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+
       
### `mkPackageOption` {#sec-option-declarations-util-mkPackageOption}

     

       
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Usage:

     

       
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···

       
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If you wish to explicitly provide no default, pass `null` as `default`.

     

       
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During the transition to CommonMark documentation `mkPackageOption` creates an option with a DocBook description attribute, once the transition is completed it will create a CommonMark description instead. `mkPackageOptionMD` always creates an option with a CommonMark description attribute and will be removed some time after the transition is completed.

     

       
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[]{#ex-options-declarations-util-mkPackageOption}

     

       
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Examples:

     

       
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::: {#ex-options-declarations-util-mkPackageOption-hello .example}

     

       
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### Simple `mkPackageOption` usage

     

       
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```nix

     

       
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lib.mkPackageOptionMD pkgs "hello" { }

     

       
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lib.mkPackageOption pkgs "hello" { }

     

       
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# is like

     

       
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lib.mkOption {

     

       
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  type = lib.types.package;

     
···

       
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::: {#ex-options-declarations-util-mkPackageOption-ghc .example}

     

       
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### `mkPackageOption` with explicit default and example

     

       
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```nix

     

       
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-
       
lib.mkPackageOptionMD pkgs "GHC" {

     

       
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+
       
lib.mkPackageOption pkgs "GHC" {

     

       
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  default = [ "ghc" ];

     

       
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  example = "pkgs.haskell.packages.ghc92.ghc.withPackages (hkgs: [ hkgs.primes ])";

     

       
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}