substitutions, Fix terms are very large when printed as trees (in 
  memory, they are quite compact due to sharing).

  The ATerm library doesn't search the heap for pointers to ATerms
  when garbage collecting.  As a result, C++ containers such as
  `map<ATerm, ATerm>' will cause pointer to be hidden from the garbage
  collector, causing crashes.  Instead, we now use ATermTables.

  semicolons instead of comma's.  Final semicolon in the set is optional.

  attribute set.

* Mutually recursive attribute sets.
* Print evaluator efficiency statistics.

  buggy.  It fails to clear an internal variable (SG_textIndex)
  between invocations, so it can be called only once during a program
  execution.

  removed, paths are absolutised relative to the path containing the
  expression we just parsed, and integer literals are converted to
  actual integers.

  friends to do the parsing.  The parse table is embedded in the Fix
  executable using bin2c, which converts an arbitrary file into a C
  character array.

  writes stdout/stderr of the builder to ${prefix}/var/log/nix/x,
  where x is the file name of the derivation expression, e.g.,

    /nix/var/log/nix/54256391624be04fcb426048ae3ea0a4-d-pan-0.14.2.nix

  Note that consecutive builds of the same expression overwrite,
  rather than append to, existing log files.

  handles are closed when they go out of scope.

* Fixed a segfault caused by the buffering of stderr.
* Fix now allows the specification of the full output path.  This
  should be used with great care, since it by-passes the normal hash
  generation.
* Incremented the version number to 0.4 (prerelease).

* Fixed svn:ignore on externals/.

  log on commit.  This means that there is a small change that some
  transactions may be rolled back in case of a system crash, but this
  should not be a problem (it merely might cause some expression
  realisations to be rolled back), and it vastly improves performance.

* Upgraded to ATerm 2.0.5 (which also includes Armijn's 64-bit
  patches).