The value pointers of lists with 1 or 2 elements are now stored in the
list value itself. In particular, this makes the "concatMap (x: if
cond then [(f x)] else [])" idiom cheaper.
We now print all output paths of a package, e.g.
openssl-1.0.0i bin=/nix/store/gq2mvh0wb9l90djvsagln3aqywqmr6vl-openssl-1.0.0i-bin;man=/nix/store/7zwf5r5hsdarl3n86dasvb4chm2xzw9n-openssl-1.0.0i-man;/nix/store/cj7xvk7fjp9q887359j75pw3pzjfmqf1-openssl-1.0.0i
or (in XML mode)
<item attrPath="openssl" name="openssl-1.0.0i" system="x86_64-linux">
<output name="bin" path="/nix/store/gq2mvh0wb9l90djvsagln3aqywqmr6vl-openssl-1.0.0i-bin" />
<output name="man" path="/nix/store/7zwf5r5hsdarl3n86dasvb4chm2xzw9n-openssl-1.0.0i-man" />
<output name="out" path="/nix/store/cj7xvk7fjp9q887359j75pw3pzjfmqf1-openssl-1.0.0i" />
</item>
tree). This saves a lot of memory. The vector should be sorted so
that names can be looked up using binary search, but this is not the
case yet. (Surprisingly, looking up attributes using linear search
doesn't have a big impact on performance.)
Memory consumption for
$ nix-instantiate /etc/nixos/nixos/tests -A bittorrent.test --readonly-mode
on x86_64-linux with GC enabled is now 185 MiB (compared to 946
MiB on the trunk).
a pointer to a Value, rather than the Value directly. This improves
the effectiveness of garbage collection a lot: if the Value is
stored inside the set directly, then any live pointer to the Value
causes all other attributes in the set to be live as well.
values. This improves sharing and gives another speed up.
Evaluation of the NixOS system attribute is now almost 7 times
faster than the old evaluator.
efficiently. The symbol table ensures that there is only one copy
of each symbol, thus allowing symbols to be compared efficiently
using a pointer equality test.
Nix expressions in that directory are combined into an attribute set
{file1 = import file1; file2 = import file2; ...}, i.e. each Nix
expression is an attribute with the file name as the attribute
name. Also recurses into directories.
* nix-env: removed the "--import" (-I) option which set the
~/.nix-defexpr symlink.
* nix-channel: don't use "nix-env --import", instead symlink
~/.nix-defexpr/channels. So finally nix-channel --update doesn't
override any default Nix expressions but combines with them.
This means that you can have (say) a local Nixpkgs SVN tree and use
it as a default for nix-env:
$ ln -s .../path-to-nixpkgs-tree ~/.nix-defexpr/nixpkgs_svn
and be subscribed to channels (including Nixpkgs) at the same time.
(If there is any ambiguity, the -A flag can be used to
disambiguate, e.g. "nix-env -i -A nixpkgs_svn.pan".)
get the basename of the channel URL (e.g., nixpkgs-unstable). The
top-level Nix expression of the channel is now an attribute set, the
attributes of which are the individual channels (e.g.,
{nixpkgs_unstable = ...; strategoxt_unstable = ...}). This makes
attribute paths ("nix-env -qaA" and "nix-env -iA") more sensible,
e.g., "nix-env -iA nixpkgs_unstable.subversion".
by priority and version install. That is, if there are multiple
packages with the same name, then pick the package with the highest
priority, and only use the version if there are multiple packages
with the same priority.
This makes it possible to mark specific versions/variant in Nixpkgs
more or less desirable than others. A typical example would be a
beta version of some package (e.g., "gcc-4.2.0rc1") which should not
be installed even though it is the highest version, except when it
is explicitly selected (e.g., "nix-env -i gcc-4.2.0rc1").
* Idem for nix-env -u, only the semantics are a bit trickier since we
also need to take into account the priority of the currently
installed package (we never upgrade to a lower priority, unless
--always is given).
attribute) about installed packages in user environments. Thus, an
operation like `nix-env -q --description' shows useful information
not only on available packages but also on installed packages.
* nix-env now passes the entire manifest as an argument to the Nix
expression of the user environment builder (not just a list of
paths), so that in particular the user environment builder has
access to the meta attributes.
* New operation `--set-flag' in nix-env to change meta info of
installed packages. This will be useful to pass per-package
policies to the user environment builder (e.g., how to resolve
collision or whether to disable a package (NIX-80)) or upgrade
policies in nix-env (e.g., that a package should be "masked", that
is, left untouched by upgrade actions). Example:
$ nix-env --set-flag enabled false ghc-6.4
concatenation and string coercion. This was a big mess (see
e.g. NIX-67). Contexts are now folded into strings, so that they
don't cause evaluation errors when they're not expected. The
semantics of paths has been clarified (see nixexpr-ast.def).
toString() and coerceToString() have been merged.
Semantic change: paths are now copied to the store when they're in a
concatenation (and in most other situations - that's the
formalisation of the meaning of a path). So
"foo " + ./bla
evaluates to "foo /nix/store/hash...-bla", not "foo
/path/to/current-dir/bla". This prevents accidental impurities, and
is more consistent with the treatment of derivation outputs, e.g.,
`"foo " + bla' where `bla' is a derivation. (Here `bla' would be
replaced by the output path of `bla'.)
