A list of web servers used by builtins.fetchurl to obtain files by hash. Given a hash type ht and a base-16 hash h, Lix will try to download the file from hashed-mirror/ht/h. This allows files to be downloaded even if they have disappeared from their original URI. For example, given an example mirror http://tarballs.nixos.org/, when building the derivation

builtins.fetchurl {
  url = "https://example.org/foo-1.2.3.tar.xz";
  sha256 = "2c26b46b68ffc68ff99b453c1d30413413422d706483bfa0f98a5e886266e7ae";
}

Lix will attempt to download this file from http://tarballs.nixos.org/sha256/2c26b46b68ffc68ff99b453c1d30413413422d706483bfa0f98a5e886266e7ae first. If it is not available there, if will try the original URI.