[Nix-dev] Nix 0.9 released

[Eelco Dolstra]

Hi,

I'm pleased to announce the availability of a new stable release of the
Nix Deployment System.  Release 0.9 can be found at

    http://nix.cs.uu.nl/dist/nix/nix-0.9/

NOTE: this version of Nix uses Berkeley DB 4.3 instead of 4.2. The database is
upgraded automatically, but you should be careful not to use old versions of
Nix that still use Berkeley DB 4.2. In particular, if you use a Nix installed
through Nix, you should run

    $ nix-store --clear-substitutes

first.

  * Unpacking of patch sequences is much faster now since we no longer do
    redundant unpacking and repacking of intermediate paths.

  * Nix now uses Berkeley DB 4.3.

  * The `derivation' primitive is lazier. Attributes of dependent derivations
    can mutually refer to each other (as long as there are no data dependencies
    on the `outPath' and `drvPath' attributes computed by `derivation').

    For example, 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.

    Also, it 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).

  * `nix-build' now defaults to using `./default.nix' if no Nix expression is
    specified.

  * `nix-instantiate', when applied to a Nix expression that evaluates to a
    function, will call the function automatically if all its arguments have
    defaults.

  * Nix now uses libtool to build dynamic libraries. This reduces the size of
    executables.

  * A new list concatenation operator `++'. For example, `[1 2 3] ++ [4 5 6]'
    evaluates to `[1 2 3 4 5 6]'.

  * Some currently undocumented primops to support low-level build management
    using Nix (i.e., using Nix as a Make replacement). See the commit messages
    for `r3578' and `r3580'.

  * Various bug fixes and performance improvements.

-- 
Eelco Dolstra | http://www.cs.uu.nl/~eelco