so that we don't produce un-wellformed XML.

  automatically.

    [1 2 3] ++ [4 5 6] => [1 2 3 4 5 6]

  working when PATH is unset.

  (closed(closed(closed(...)))) since this reduces performance by
  producing bigger terms and killing caching (which incidentally also
  prevents useful infinite recursion detection).

* Add lexical restrictions for keywords.

  So when using Nix as a build tool, you can just say `nix-build' and
  it will build the top-level derivation defined in `default.nix'.

  with default values automatically.  I.e., e -> e {}.

  This feature makes convenience expressions such as
  pkgs/system/i686-linux.nix in Nixpkgs obsolete, since we can just do

  $ nix-instantiate ./pkgs/system/all-packages.nix

  since all-packages.nix takes a single argument (system) that has a
  default value (__thisSystem).

  handle it.  It crashed on the 234 MB tetex archive.  Probably we
  will never be able to handle archives of that size on 32-bit
  machines (because bsdiff does everything in memory requiring
  max(17*n,9*n+m)+O(1) bytes, so the address space simply isn't
  there).

  `removeAttrs attrs ["x", "y"]' returns the set `attrs' with the
  attributes named `x' and `y' removed.  It is not an error for the
  named attributes to be missing from the input set.

  unpacking and repacking of intermediate paths.

  they cause Nix builds to have unnecessary retained dependences
  (e.g., on Subversion).

  makes most query and installation operations much faster (e.g.,
  `nix-env -qa' on the current Nixpkgs is about 10 times faster).

* Make the `derivation' primitive much more lazy.  The expression
  `derivation attrs' now evaluates to (essentially)

    attrs // {
      type = "derivation";
      outPath = derivation! attrs;
      drvPath = derivation! attrs;
    }

  where `derivation!' is a primop that does the actual derivation
  instantiation (i.e., it does what `derivation' used to do).  The
  advantage is that it allows commands such as `nix-env -qa' and
  `nix-env -i' to be much faster since they no longer need to
  instantiate all derivations, just the `name' attribute.  (However,
  `nix-env' doesn't yet take advantage of this since it still always
  evaluates the `outPath' and `drvPath' attributes).

  Also, this allows derivations to cyclically reference each other,
  for example,

    webServer = derivation {
      ...
      hostName = "svn.cs.uu.nl";
      services = [svnService];
    };

    svnService = derivation {
      ...
      hostName = webServer.hostName;
    };

  Previously, this would yield a black hole (infinite recursion).

  also part of ISO C).

* `compare' in GCC 2.95 is broken.

  should not have worked at all.