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Added makeExtensibleWithInterface

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This commit is contained in:
Will Fancher 2017-07-11 21:33:26 -04:00
parent 2c1097a83b
commit 08021dd825
1 changed files with 15 additions and 4 deletions
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19
lib/fixed-points.nix
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@ -71,8 +71,19 @@ rec {
# Same as `makeExtensible` but the name of the extending attribute is
# customized.
makeExtensibleWithCustomName = extenderName: rattrs:
fix' rattrs // {
${extenderName} = f: makeExtensibleWithCustomName extenderName (extends f rattrs);
};
makeExtensibleWithCustomName = extenderName: makeExtensibleWithInterface
(fixedPoint: extend: fixedPoint // { ${extenderName} = extend; });
# Similar to `makeExtensible`, but expects you to implement the
# final interface for the result. Specifically, it takes an extra
# argument: a function that takes the final result and the `extend`
# function as arguments, and returns a transformed result
# (preferably one that contains the `extend` function). This is
# mainly useful for getting to choose what to name the `extend`
# function in the resulting attribute set. But it's also useful for
# having an internal structure that extensions can see, but the user
# facing code cannot.
makeExtensibleWithInterface = interface: fext: interface
(fix' fext)
(f: makeExtensibleWithInterface interface (extends f fext));
}