The major changes are: * The evaluation is now driven by the declared options. In particular, this fixes the long-standing problem with lack of laziness of disabled option definitions. Thus, a configuration like config = mkIf false { environment.systemPackages = throw "bla"; }; will now evaluate without throwing an error. This also improves performance since we're not evaluating unused option definitions. * The implementation of properties is greatly simplified. * There is a new type constructor "submodule" that replaces "optionSet". Unlike "optionSet", "submodule" gets its option declarations as an argument, making it more like "listOf" and other type constructors. A typical use is: foo = mkOption { type = type.attrsOf (type.submodule ( { config, ... }: { bar = mkOption { ... }; xyzzy = mkOption { ... }; })); }; Existing uses of "optionSet" are automatically mapped to "submodule". * Modules are now checked for unsupported attributes: you get an error if a module contains an attribute other than "config", "options" or "imports". * The new implementation is faster and uses much less memory. |
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.. | ||
doc | ||
gui | ||
lib | ||
maintainers | ||
modules | ||
tests | ||
.topmsg | ||
COPYING | ||
default.nix | ||
README | ||
release-combined.nix | ||
release.nix |
*** NixOS *** NixOS is a Linux distribution based on the purely functional package management system Nix. More information can be found at http://nixos.org/nixos and in the manual in doc/manual.