format: lib/fixed-points
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@ -63,7 +63,6 @@ rec {
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See [`extends`](#function-library-lib.fixedPoints.extends) for an example use case.
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There `self` is also often called `final`.
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# Inputs
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`f`
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@ -90,7 +89,12 @@ rec {
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:::
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*/
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fix = f: let x = f x; in x;
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fix =
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f:
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let
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x = f x;
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in
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x;
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/**
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A variant of `fix` that records the original recursive attribute set in the
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@ -99,14 +103,20 @@ rec {
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This is useful in combination with the `extends` function to
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implement deep overriding.
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# Inputs
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`f`
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: 1\. Function argument
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*/
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fix' = f: let x = f x // { __unfix__ = f; }; in x;
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fix' =
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f:
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let
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x = f x // {
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__unfix__ = f;
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};
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in
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x;
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/**
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Return the fixpoint that `f` converges to when called iteratively, starting
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@ -117,7 +127,6 @@ rec {
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0
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```
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# Inputs
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`f`
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@ -134,13 +143,12 @@ rec {
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(a -> a) -> a -> a
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```
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*/
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converge = f: x:
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converge =
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f: x:
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let
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x' = f x;
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in
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if x' == x
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then x
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else converge f x';
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if x' == x then x else converge f x';
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/**
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Extend a function using an overlay.
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@ -149,7 +157,6 @@ rec {
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A fixed-point function is a function which is intended to be evaluated by passing the result of itself as the argument.
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This is possible due to Nix's lazy evaluation.
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A fixed-point function returning an attribute set has the form
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```nix
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@ -257,7 +264,6 @@ rec {
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```
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:::
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# Inputs
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`overlay`
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@ -299,8 +305,7 @@ rec {
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:::
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*/
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extends =
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overlay:
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f:
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overlay: f:
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# The result should be thought of as a function, the argument of that function is not an argument to `extends` itself
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(
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final:
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@ -316,9 +321,11 @@ rec {
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*/
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composeExtensions =
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f: g: final: prev:
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let fApplied = f final prev;
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prev' = prev // fApplied;
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in fApplied // g final prev';
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let
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fApplied = f final prev;
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prev' = prev // fApplied;
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in
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fApplied // g final prev';
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/**
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Composes a list of [`overlays`](#chap-overlays) and returns a single overlay function that combines them.
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@ -342,7 +349,6 @@ rec {
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- `final` is the result of the fixed-point function, with all overlays applied.
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- `prev` is the result of the previous overlay function.
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# Type
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```
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@ -385,8 +391,7 @@ rec {
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```
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:::
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*/
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composeManyExtensions =
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lib.foldr (x: y: composeExtensions x y) (final: prev: {});
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composeManyExtensions = lib.foldr (x: y: composeExtensions x y) (final: prev: { });
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/**
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Create an overridable, recursive attribute set. For example:
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@ -414,7 +419,6 @@ rec {
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Same as `makeExtensible` but the name of the extending attribute is
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customized.
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# Inputs
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`extenderName`
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@ -425,8 +429,13 @@ rec {
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: 2\. Function argument
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*/
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makeExtensibleWithCustomName = extenderName: rattrs:
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fix' (self: (rattrs self) // {
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${extenderName} = f: makeExtensibleWithCustomName extenderName (extends f rattrs);
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});
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makeExtensibleWithCustomName =
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extenderName: rattrs:
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fix' (
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self:
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(rattrs self)
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// {
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${extenderName} = f: makeExtensibleWithCustomName extenderName (extends f rattrs);
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}
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);
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}
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