name: fetchTree args: [spec] experimentalFeature: flakes renameInGlobalScope: false

Fetches the tree specified by the attribute set or URL spec.

The spec is in the form of a flake reference; flake references are a thin wrapper around fetchTree.

There are some efforts to document the behaviour of fetchTree independently of flakes, but they have not yet borne fruit as of 2025-03.

spec also accepts the following special attribute not documented there:

• name
  The name of the resulting store path to fetch to. Optional; defaults to the basename of the URL.

  Due to some vagaries of flake behaviour, naming the fetched input source may avoid some extra copying when using the resulting store path as a path input for a flake. See https://git.lix.systems/lix-project/lix/issues/630.