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nixpkgs/pkgs/top-level/default.nix
2016-12-20 16:27:04 -08:00

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Nix

/* This function composes the Nix Packages collection. It:
1. Applies the final stage to the given `config` if it is a function
2. Infers an appropriate `platform` based on the `system` if none is
provided
3. Defaults to no non-standard config and no cross-compilation target
4. Uses the above to infer the default standard environment (stdenv) if
none is provided
5. Builds the final stage --- a fully booted package set with the chosen
stdenv
Use `impure.nix` to also infer the `system` based on the one on which
evaluation is taking place, and the configuration from environment variables
or dot-files. */
{ # The system (e.g., `i686-linux') for which to build the packages.
system
, # Allow a configuration attribute set to be passed in as an argument.
config ? {}
, # The standard environment for building packages, or rather a function
# providing it. See below for the arguments given to that function.
stdenvFunc ? import ../stdenv
, crossSystem ? null
, platform ? assert false; null
} @ args:
let # Rename the function arguments
configExpr = config;
in let
lib = import ../../lib;
# Allow both:
# { /* the config */ } and
# { pkgs, ... } : { /* the config */ }
config =
if builtins.isFunction configExpr
then configExpr { inherit pkgs; }
else configExpr;
# Allow setting the platform in the config file. Otherwise, let's use a
# reasonable default.
platform =
args.platform
or ( config.platform
or ((import ./platforms.nix).selectPlatformBySystem system) );
# A few packages make a new package set to draw their dependencies from.
# (Currently to get a cross tool chain, or forced-i686 package.) Rather than
# give `all-packages.nix` all the arguments to this function, even ones that
# don't concern it, we give it this function to "re-call" nixpkgs, inheriting
# whatever arguments it doesn't explicitly provide. This way,
# `all-packages.nix` doesn't know more than it needs too.
#
# It's OK that `args` doesn't include default arguemtns from this file:
# they'll be deterministically inferred. In fact we must *not* include them,
# because it's important that if some parameter which affects the default is
# substituted with a different argument, the default is re-inferred.
#
# To put this in concrete terms, this function is basically just used today to
# use package for a different platform for the current platform (namely cross
# compiling toolchains and 32-bit packages on x86_64). In both those cases we
# want the provided non-native `system` argument to affect the stdenv chosen.
nixpkgsFun = newArgs: import ./. (args // newArgs);
# Partially apply some arguments for building bootstraping stage pkgs
# sets. Only apply arguments which no stdenv would want to override.
allPackages = newArgs: import ./stage.nix ({
inherit lib nixpkgsFun;
} // newArgs);
stdenv = stdenvFunc {
inherit lib allPackages system platform crossSystem config;
};
pkgs = allPackages { inherit system stdenv config crossSystem platform; };
in pkgs