factor-lang = factorPackages.factor-minimal-gui;

  src = fetchFromGitHub {
    name = finalAttrs.vocabName;
    owner = "Capital-EX";
    repo = "painter";
    rev = "365797be8c4f82440bec0ad0a50f5a858a06c1b6";
    hash = "sha256-VdvnvKNGcFAtjWVDoxyYgRSyyyy0BEZ2MZGQ71O8nUI=";
  };

  sourceRoot = ".";

  enableUI = true;
  extraVocabs = [ factorPackages.bresenham ];

  extraPaths = with finalAttrs.factor-lang; binPackages ++ defaultBins ++ [ curl ];

})
```

The use of the `src.name` and`sourceRoot` attributes conveniently establish the necessary `painter` vocabulary directory that is needed for the deployment to work.

It requires the packager to specify the full set of binaries to be made available at runtime.
This enables the standard pattern for application packages to specify all runtime dependencies explicitly without the Factor runtime interfering.

`buildFactorApplication` is a wrapper around `stdenv.mkDerivation` and takes all of its attributes.
Additional attributes that are understood by `buildFactorApplication`:

*`buildDesc`* (Function or attribute set)

: A build description similar to `stdenv.mkDerivation` with the following attributes:

  `vocabName` (String; _optional_)

  : is the path to the vocabulary to be deployed relative to the source root.
    So, directory `foo/` from the example above could be `extra/deep/down/foo`.
    This allows you to maintain Factor's vocabulary hierarchy and distribute the same source tree as a stand-alone application and as a library in the Factor development environment via the `extraVocabs` attribute.

  `binName` (String; _optional_)

  : is the name of the resulting binary in `/bin/`.
    It defaults to the last directory component in `vocabName`.
    It is also added as the `meta.mainProgram` attribute to facilitate `nix run`.

  `enableUI` (Boolean; _optional_)

  : is `false` by default.
    Set this to `true` when you ship a graphical application.

  `extraLibs` (List; _optional_)

  : adds additional libraries as runtime dependencies.
    Defaults to `[]` and is concatenated with `runtimeLibs` from the used factor-lang package.
    Use `factor-minimal` to minimize the closure of runtime libraries.

  `extraPaths` (List; _optional_)

  : adds additional binaries to the runtime PATH environment variable (without adding their libraries, as well).
    Defaults to `[]` and is concatenated with `defaultBins` and `binPackages` from the used factor-lang package.
    Use `factor-minimal` to minimize the closure of runtime libraries.

  `deployScriptText` (String; _optional_)

  : is the actual deploy Factor file that is executed to deploy the application.
    You can change it if you need to perform additional computation during deployment.

  `factor-lang` (Package; _optional_)

  : overrides the Factor package to use to deploy this application, which also affects the default library bindings and programs in the runtime PATH.
    It defaults to `factor-lang` when `enableUI` is turned on and `factor-no-gui` when it is turned off.
    Applications that use only Factor libraries without external bindings or programs may set this to `factor-minimal` or `factor-minimal-gui`.