representation of closures as ATerms in the Nix store. Instead, the
file system pointer graph is now stored in the Nix database. This
has many advantages:
- It greatly simplifies the implementation (we can drop the notion
of `successors', and so on).
- It makes registering roots for the garbage collector much easier.
Instead of specifying the closure expression as a root, you can
simply specify the store path that must be retained as a root.
This could not be done previously, since there was no way to find
the closure store expression containing a given store path.
- Better traceability: it is now possible to query what paths are
referenced by a path, and what paths refer to a path.
profile. Arguments are either generation number, or `old' to delete
all non-current generations. Typical use:
$ nix-env --delete-generations old
$ nix-collect-garbage
* istringstream -> string2Int.
derivation (i.e., the closure store expression) a root of the
garbage collector. This ensures that running `nix-collect-garbage
--no-successors' is safe.
