Hovering over the abbreviated path will reveal the full path.  This
  probably only works in Mozilla. 

  build logs.  The program `log2xml' converts a Nix build log (read
  from standard input) into XML file that can then be converted to
  XHTML by the `log2html.xsl' stylesheet.  The CSS stylesheet
  `logfile.css' is necessary to make it look good.

  This is primarily useful if the log file has a *tree structure*,
  i.e., that sub-tasks such as the various phases of a build (unpack,
  configure, make, etc.) or recursive invocations of Make are
  represented as such.  While a log file is in principle an
  unstructured plain text file, builders can communicate this tree
  structure to `log2xml' by using escape sequences:

  - "\e[p" starts a new nesting level; the first line following the
    escape code is the header;

  - "\e[q" ends the current nesting level.

  The generic builder in nixpkgs (not yet committed) uses this.  It
  shouldn't be to hard to patch GNU Make to speak this protocol.

  Further improvements to the generated HTML pages are to allow
  collapsing/expanding of subtrees, and to abbreviate store paths (but
  to show the full path by hovering the mouse over it).
  

  builders to point to the store and the temporary build directory,
  respectively.  Useful for purity checking.
* Also set TEMPDIR, TMPDIR, TEMP, and TEMP to NIX_BUILD_TOP to make
  sure that tools in the builder store temporary files in the right
  location.

  b then x else y.z'.

* Do not create stuff in localstatedir when doing `make install'
  (since we may not have write access).  In general, installation of
  constant code/data should be separate from the initialisation of
  mutable state.

  non-inherited attributes.

  chroot() environment.
* A operation `--validpath' to register path validity.  Useful for
  bootstrapping in a pure Nix environment.
* Safety checks: ensure that files involved in store operations are in
  the store.

  Otherwise the substitute mechanism can break in subtle ways.

  derivation (i.e., the closure store expression) a root of the
  garbage collector.  This ensures that running `nix-collect-garbage
  --no-successors' is safe.

* nix-pull now requires the full url to the manifest, i.e.,
  `/MANIFEST/' is no longer automatically appended.
* nix-prefetch-url works again.  

  whether we want to upgrade if the current version is less than the
  available version (default), when it is less or equal, or always.
  
* Added a flag `--dry-run' to show what would happen in `--install',
  `--uninstall', and `--upgrade', without actually performing the
  operation.

  of the current profile, e.g.,

    $ nix-env --list-generations
    ...
    39   2004-02-02 17:53:53
    40   2004-02-02 17:55:18
    41   2004-02-02 17:55:41
    42   2004-02-02 17:55:50   (current)

    $ nix-env --switch-generation 39

    $ ls -l /nix/var/nix/profiles/default
    ... default -> default-39-link

* Also a command `--rollback' which is just a convenience operation to
  rollback to the oldest generation younger than the current one.

  Note that generations properly form a tree.  E.g., if after
  switching to generation 39, we perform an installation action,
  a generation 43 is created which is a descendant of 39, not 42.  So
  a rollback from 43 ought to go back to 39.  This is not currently
  implemented; generations form a linear sequence.

  profile.

  argument is specified.

  default -> default-94-link
  default-82-link -> /nix/store/cc4480...
  default-83-link -> /nix/store/caeec8...
  ...
  default-94-link -> /nix/store/2896ca...
  experimental -> experimental-2-link
  experimental-1-link -> /nix/store/cc4480...
  experimental-2-link -> /nix/store/a3148f...

* `--profile' / `-p' -> `--switch-profile' / `-S'
* `--link' / `-l' -> `--profile' / `-p'
* The default profile is stored in $prefix/var/nix/profiles.
  $prefix/var/nix/links is gone.  Profiles can be stored anywhere.
* The current profile is now referenced from ~/.nix-profile, not
  ~/.nix-userenv.
* The roots to the garbage collector now have extension `.gcroot', not
  `.id'.

  other attribute sets, rather than the current scope.  E.g.,
  
    {inherit (pkgs) gcc binutils;}

  is equivalent to

    {gcc = pkgs.gcc; binutils = pkgs.binutils;}

  I am not so happy about the syntax.

  {x=1; y=2; z=3;} // {y=4;}  =>  {x=1; y=4; z=3;}

* Various performance improvements in the evaluator.
* Do not link against unused (and missing!) libraries (-lsglr, etc.).

  `inherit' variables from the surrounding lexical scope.

  E.g.,

    {stdenv, libfoo}: derivation {
      builder = ./bla;
      inherit stdenv libfoo;
      xyzzy = 1;
    }

  is equivalent to

    {stdenv, libfoo}: derivation {
      builder = ./bla;
      stdenv = stdenv;
      libfoo = libfoo;
      xyzzy = 1;
    }

  Note that for mutually recursive attribute set definitions (`rec
  {...}'), this also works, that is, `rec {inherit x;}' is equivalent
  to `let {fresh = x; body = rec {x = fresh;};}', *not*
  `rec {x = x}'.

* `--version' flag for all commands.
* Manual updates.

* Include missing files in distributions.

  parser (roughly 80x faster).

  The absolutely latest version of Bison (1.875c) is required for
  reentrant GLR support, as well as a recent version of Flex (say,
  2.5.31).  Note that most Unix distributions ship with the
  prehistoric Flex 2.5.4, which doesn't support reentrancy.