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.

  any substitutes for the derivation.

  ATermMaps.  Found thanks to Valgrind!

* Updated the README.  Now it just refers to the manual.

  Nix.  This is to prevent Berkeley DB from becoming wedged.

  Unfortunately it is not possible to throw C++ exceptions from a
  signal handler.  In fact, you can't do much of anything except
  change variables of type `volatile sig_atomic_t'.  So we set an
  interrupt flag in the signal handler and check it at various
  strategic locations in the code (by calling checkInterrupt()).
  Since this is unlikely to cover all cases (e.g., (semi-)infinite
  loops), sometimes SIGTERM may now be required to kill Nix.

  the output path of a derivation, not the path of its store
  expression.  This ensures that changes that affect the path of the
  store expression but not the output path, do not affect the
  `installed' state of a derivation.

* Use curl instead of wget.

  files.  Target location is no longer hard-coded; it accepts a number
  of URLs on the command line.

* `nix-install-package': compatibility fixes.

  verbosity level.

  recovery fails.

  (following the Usenix paper).

* Some CSS tweaks.