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9279174dde
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).
19 lines
409 B
Nix
19 lines
409 B
Nix
let
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f = args@{x, y, z}: x + args.y + z;
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g = {x, y, z}@args: f args;
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h = {x ? "d", y ? x, z ? args.x}@args: x + y + z;
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i = args@args2: args.x + args2.y;
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j = {x, y, z, ...}: x + y + z;
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in
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f {x = "a"; y = "b"; z = "c";} +
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g {x = "x"; y = "y"; z = "z";} +
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h {x = "D";} +
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h {x = "D"; y = "E"; z = "F";} +
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i {x = "g"; y = "h";} +
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j {x = "i"; y = "j"; z = "k"; bla = "bla"; foo = "bar";}
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