in attribute set pattern matches. This allows defining a function
that takes *at least* the listed attributes, while ignoring
additional attributes. For instance,
{stdenv, fetchurl, fuse, ...}:
stdenv.mkDerivation {
...
};
defines a function that requires an attribute set that contains the
specified attributes but ignores others. The main advantage is that
we can then write in all-packages.nix
aefs = import ../bla/aefs pkgs;
instead of
aefs = import ../bla/aefs {
inherit stdenv fetchurl fuse;
};
This saves a lot of typing (not to mention not having to update
all-packages.nix with purely mechanical changes). It saves as much
typing as the "args: with args;" style, but has the advantage that
the function arguments are properly declared (not implicit in what
the body of the "with" uses).
functions that take a single argument (plain lambdas) into one AST
node (Function) that contains a Pattern node describing the
arguments. Current patterns are single lazy arguments (VarPat) and
matching against an attribute set (AttrsPat).
This refactoring allows other kinds of patterns to be added easily,
such as Haskell-style @-patterns, or list pattern matching.
again. (After the previous substituter mechanism refactoring I
didn't update the code that obtains the references of substitutable
paths.) This required some refactoring: the substituter programs
are now kept running and receive/respond to info requests via
stdin/stdout.
logic through the `parseDrvName' and `compareVersions' primops.
This will allow expressions to easily check whether some dependency
is a specific needed version or falls in some version range. See
tests/lang/eval-okay-versions.nix for examples.
single quotes. Example (from NixOS):
job = ''
start on network-interfaces
start script
rm -f /var/run/opengl-driver
${if videoDriver == "nvidia"
then "ln -sf ${nvidiaDrivers} /var/run/opengl-driver"
else if cfg.driSupport
then "ln -sf ${mesa} /var/run/opengl-driver"
else ""
}
rm -f /var/log/slim.log
end script
'';
This style has two big advantages:
- \, ' and " aren't special, only '' and ${. So you get a lot less
escaping in shell scripts / configuration files in Nixpkgs/NixOS.
The delimiter '' is rare in scripts (and can usually be written as
""). ${ is also fairly rare.
Other delimiters such as <<...>>, {{...}} and <|...|> were also
considered but this one appears to have the fewest drawbacks
(thanks Martin).
- Indentation is intelligently stripped so that multi-line strings
can follow the nesting structure of the containing Nix
expression. E.g. in the example above 6 spaces are stripped from
the start of each line. This prevents unnecessary indentation in
generated files (which sometimes even breaks things).
See tests/lang/eval-okay-ind-string.nix for some examples.
$ nix-env -e $(which firefox)
or
$ nix-env -e /nix/store/nywzlygrkfcgz7dfmhm5xixlx1l0m60v-pan-0.132
* nix-env -i: if an argument contains a slash anywhere, treat it as a
path and follow it through symlinks into the Nix store. This allows
things like
$ nix-build -A firefox
$ nix-env -i ./result
* nix-env -q/-i/-e: don't complain when the `*' selector doesn't match
anything. In particular, `nix-env -q \*' doesn't fail anymore on an
empty profile.
derivations that produce the same output path don't work properly
wrt locking. This happens a lot in the build farm when fetchurl
derivations downloading the same file on different platforms are
executed in parallel and then copied back to the main machine.
* `sub' to subtract two numbers.
* `stringLength' to get the length of a string.
* `substring' to get a substring of a string. These should be enough
to allow most string operations to be expressed.
from a source directory. All files for which a predicate function
returns true are copied to the store. Typical example is to leave
out the .svn directory:
stdenv.mkDerivation {
...
src = builtins.filterSource
(path: baseNameOf (toString path) != ".svn")
./source-dir;
# as opposed to
# src = ./source-dir;
}
This is important because the .svn directory influences the hash in
a rather unpredictable and variable way.
attribute existence and to return an attribute from an attribute
set, respectively. Example: `hasAttr "foo" {foo = 1;}'. They
differ from the `?' and `.' operators in that the attribute name is
an arbitrary expression. (NIX-61)
* `nix-install-package --help' (NIX-9).
* `nix-install-package --non-interactive': don't prompt or pause.
* Tests for nix-install-package.
* Security fixes: filter the values obtained from the nixpkg.
and returns its path. This can be used to (for instance) write
builders inside a Nix expression, e.g.,
stdenv.mkDerivation {
builder = "
source $stdenv/setup
...
";
...
}
all the primops. This allows Nix expressions to test for new
primops and take appropriate action if they're not available. For
instance, rather than calling a primop `foo' directly, they could
say `if builtins ? foo then builtins.foo ... else ...'.
argument has a valid value, i.e., is in a certain domain. E.g.,
{ foo : [true false]
, bar : ["a" "b" "c"]
}: ...
This previously could be done using assertions, but domain checks
will allow the buildfarm to automatically extract the configuration
space from functions.
"--with-freetype2-library=" + freetype + "/lib"
can now be written as
"--with-freetype2-library=${freetype}/lib"
An arbitrary expression can be enclosed within ${...}, not just
identifiers.
* Escaping in string literals: \n, \r, \t interpreted as in C, any
other character following \ is interpreted as-is.
* Newlines are now allowed in string literals.
externals directory. This is in particular useful because though
most systems have bzip2/bunzip2, they don't always have libbz2,
which we need for bsdiff/bspatch.
packages (provided that they have a `meta.description' attribute).
E.g.,
$ ./src/nix-env/nix-env -qa --description gcc
gcc-4.0.2 GNU Compiler Collection, 4.0.x (cross-compiler for sparc-linux)
gcc-4.0.2 GNU Compiler Collection, 4.0.x (cross-compiler for mips-linux)
gcc-4.0.2 GNU Compiler Collection, 4.0.x (cross-compiler for arm-linux)
gcc-4.0.2 GNU Compiler Collection, 4.0.x
to be queried, e.g., `nix-env -qa firefox'. This does require the
argument '*' to be passed if one wants information about all
derivations, so the old `nix-env -qa' now is `nix-env -qa "*"'.
nix-store query options `--referer' and `--referer-closure' have
been changed to `--referrer' and `--referrer-closure' (but the old
ones are still accepted for compatibility).
`removeAttrs attrs ["x", "y"]' returns the set `attrs' with the
attributes named `x' and `y' removed. It is not an error for the
named attributes to be missing from the input set.
* Removed some dead code (successor stuff) from nix-push.
* Updated terminology in the tests (store expr -> drv path).
* Check that the deriver is set properly in the tests.
being created after the garbage collector has read the temproots
directory. This blocks the creation of new processes, but the
garbage collector could periodically release the GC lock to allow
them to run.
roots to a per-process temporary file in /nix/var/nix/temproots
while holding a write lock on that file. The garbage collector
acquires read locks on all those files, thus blocking further
progress in other Nix processes, and reads the sets of temporary
roots.
