lib.filesystem: Minor refactor

let

  inherit (builtins)

    getAttr

    readDir

    pathExists

    ;

  /*

    Returns the type of a path: regular (for file), symlink, or directory.

  */

  pathType = path: getAttr (baseNameOf path) (readDir (dirOf path));

  pathType = path:

    (readDir (dirOf path)).${baseNameOf path};

  /*

    Returns true if the path exists and is a directory, false otherwise.

  */

  pathIsDirectory = path: if pathExists path then (pathType path) == "directory" else false;

  pathIsDirectory = path:

    pathExists path && pathType path == "directory";

  /*

    Returns true if the path exists and is a regular file, false otherwise.

  */

  pathIsRegularFile = path: if pathExists path then (pathType path) == "regular" else false;

  pathIsRegularFile = path:

    pathExists path && pathType path == "regular";

  /*

    A map of all haskell packages defined in the given path,