mirror of
https://github.com/NixOS/nixpkgs.git
synced 2024-12-15 02:03:01 +00:00
1081 lines
19 KiB
Nix
1081 lines
19 KiB
Nix
{ lib }:
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let
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inherit (lib.trivial)
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isFunction
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isInt
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functionArgs
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pathExists
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release
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setFunctionArgs
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toBaseDigits
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version
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versionSuffix
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warn;
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in {
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## Simple (higher order) functions
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/**
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The identity function
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For when you need a function that does “nothing”.
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# Inputs
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`x`
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: The value to return
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# Type
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```
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id :: a -> a
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```
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*/
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id = x: x;
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/**
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The constant function
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Ignores the second argument. If called with only one argument,
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constructs a function that always returns a static value.
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# Inputs
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`x`
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: Value to return
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`y`
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: Value to ignore
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# Type
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```
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const :: a -> b -> a
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```
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# Examples
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:::{.example}
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## `lib.trivial.const` usage example
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```nix
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let f = const 5; in f 10
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=> 5
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```
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:::
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*/
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const =
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x:
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y: x;
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/**
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Pipes a value through a list of functions, left to right.
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# Inputs
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`value`
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: Value to start piping.
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`fns`
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: List of functions to apply sequentially.
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# Type
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```
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pipe :: a -> [<functions>] -> <return type of last function>
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```
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# Examples
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:::{.example}
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## `lib.trivial.pipe` usage example
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```nix
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pipe 2 [
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(x: x + 2) # 2 + 2 = 4
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(x: x * 2) # 4 * 2 = 8
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]
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=> 8
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# ideal to do text transformations
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pipe [ "a/b" "a/c" ] [
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# create the cp command
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(map (file: ''cp "${src}/${file}" $out\n''))
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# concatenate all commands into one string
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lib.concatStrings
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# make that string into a nix derivation
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(pkgs.runCommand "copy-to-out" {})
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]
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=> <drv which copies all files to $out>
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The output type of each function has to be the input type
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of the next function, and the last function returns the
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final value.
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```
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:::
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*/
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pipe = builtins.foldl' (x: f: f x);
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# note please don’t add a function like `compose = flip pipe`.
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# This would confuse users, because the order of the functions
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# in the list is not clear. With pipe, it’s obvious that it
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# goes first-to-last. With `compose`, not so much.
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## Named versions corresponding to some builtin operators.
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/**
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Concatenate two lists
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# Inputs
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`x`
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: 1\. Function argument
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`y`
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: 2\. Function argument
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# Type
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```
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concat :: [a] -> [a] -> [a]
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```
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# Examples
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:::{.example}
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## `lib.trivial.concat` usage example
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```nix
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concat [ 1 2 ] [ 3 4 ]
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=> [ 1 2 3 4 ]
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```
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:::
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*/
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concat = x: y: x ++ y;
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/**
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boolean “or”
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# Inputs
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`x`
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: 1\. Function argument
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`y`
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: 2\. Function argument
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*/
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or = x: y: x || y;
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/**
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boolean “and”
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# Inputs
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`x`
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: 1\. Function argument
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`y`
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: 2\. Function argument
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*/
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and = x: y: x && y;
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/**
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boolean “exclusive or”
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# Inputs
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`x`
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: 1\. Function argument
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`y`
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: 2\. Function argument
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*/
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# We explicitly invert the arguments purely as a type assertion.
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# This is invariant under XOR, so it does not affect the result.
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xor = x: y: (!x) != (!y);
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/**
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bitwise “not”
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*/
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bitNot = builtins.sub (-1);
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/**
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Convert a boolean to a string.
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This function uses the strings "true" and "false" to represent
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boolean values. Calling `toString` on a bool instead returns "1"
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and "" (sic!).
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# Inputs
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`b`
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: 1\. Function argument
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# Type
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```
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boolToString :: bool -> string
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```
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*/
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boolToString = b: if b then "true" else "false";
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/**
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Merge two attribute sets shallowly, right side trumps left
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mergeAttrs :: attrs -> attrs -> attrs
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# Inputs
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`x`
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: Left attribute set
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`y`
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: Right attribute set (higher precedence for equal keys)
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# Examples
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:::{.example}
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## `lib.trivial.mergeAttrs` usage example
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```nix
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mergeAttrs { a = 1; b = 2; } { b = 3; c = 4; }
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=> { a = 1; b = 3; c = 4; }
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```
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:::
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*/
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mergeAttrs =
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x:
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y: x // y;
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/**
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Flip the order of the arguments of a binary function.
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# Inputs
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`f`
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: 1\. Function argument
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`a`
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: 2\. Function argument
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`b`
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: 3\. Function argument
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# Type
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```
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flip :: (a -> b -> c) -> (b -> a -> c)
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```
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# Examples
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:::{.example}
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## `lib.trivial.flip` usage example
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```nix
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flip concat [1] [2]
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=> [ 2 1 ]
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```
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:::
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*/
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flip = f: a: b: f b a;
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/**
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Apply function if the supplied argument is non-null.
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# Inputs
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`f`
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: Function to call
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`a`
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: Argument to check for null before passing it to `f`
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# Examples
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:::{.example}
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## `lib.trivial.mapNullable` usage example
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```nix
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mapNullable (x: x+1) null
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=> null
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mapNullable (x: x+1) 22
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=> 23
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```
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:::
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*/
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mapNullable =
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f:
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a: if a == null then a else f a;
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# Pull in some builtins not included elsewhere.
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inherit (builtins)
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pathExists readFile isBool
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isInt isFloat add sub lessThan
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seq deepSeq genericClosure
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bitAnd bitOr bitXor;
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## nixpkgs version strings
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/**
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Returns the current full nixpkgs version number.
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*/
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version = release + versionSuffix;
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/**
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Returns the current nixpkgs release number as string.
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*/
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release = lib.strings.fileContents ./.version;
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/**
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The latest release that is supported, at the time of release branch-off,
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if applicable.
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Ideally, out-of-tree modules should be able to evaluate cleanly with all
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supported Nixpkgs versions (master, release and old release until EOL).
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So if possible, deprecation warnings should take effect only when all
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out-of-tree expressions/libs/modules can upgrade to the new way without
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losing support for supported Nixpkgs versions.
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This release number allows deprecation warnings to be implemented such that
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they take effect as soon as the oldest release reaches end of life.
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*/
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oldestSupportedRelease =
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# Update on master only. Do not backport.
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2311;
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/**
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Whether a feature is supported in all supported releases (at the time of
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release branch-off, if applicable). See `oldestSupportedRelease`.
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# Inputs
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`release`
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: Release number of feature introduction as an integer, e.g. 2111 for 21.11.
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Set it to the upcoming release, matching the nixpkgs/.version file.
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*/
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isInOldestRelease =
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release:
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release <= lib.trivial.oldestSupportedRelease;
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/**
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Returns the current nixpkgs release code name.
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On each release the first letter is bumped and a new animal is chosen
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starting with that new letter.
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*/
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codeName = "Uakari";
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/**
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Returns the current nixpkgs version suffix as string.
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*/
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versionSuffix =
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let suffixFile = ../.version-suffix;
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in if pathExists suffixFile
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then lib.strings.fileContents suffixFile
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else "pre-git";
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/**
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Attempts to return the the current revision of nixpkgs and
|
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returns the supplied default value otherwise.
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||
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# Inputs
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`default`
|
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|
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: Default value to return if revision can not be determined
|
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|
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# Type
|
||
|
||
```
|
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revisionWithDefault :: string -> string
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```
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*/
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revisionWithDefault =
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default:
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let
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revisionFile = "${toString ./..}/.git-revision";
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gitRepo = "${toString ./..}/.git";
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in if lib.pathIsGitRepo gitRepo
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then lib.commitIdFromGitRepo gitRepo
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else if lib.pathExists revisionFile then lib.fileContents revisionFile
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else default;
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nixpkgsVersion = warn "lib.nixpkgsVersion is a deprecated alias of lib.version." version;
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|
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/**
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Determine whether the function is being called from inside a Nix
|
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shell.
|
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|
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# Type
|
||
|
||
```
|
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inNixShell :: bool
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||
```
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*/
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inNixShell = builtins.getEnv "IN_NIX_SHELL" != "";
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|
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/**
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Determine whether the function is being called from inside pure-eval mode
|
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by seeing whether `builtins` contains `currentSystem`. If not, we must be in
|
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pure-eval mode.
|
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|
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# Type
|
||
|
||
```
|
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inPureEvalMode :: bool
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||
```
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*/
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inPureEvalMode = ! builtins ? currentSystem;
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## Integer operations
|
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|
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/**
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Return minimum of two numbers.
|
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|
||
|
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# Inputs
|
||
|
||
`x`
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||
|
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: 1\. Function argument
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`y`
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|
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: 2\. Function argument
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*/
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min = x: y: if x < y then x else y;
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|
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/**
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Return maximum of two numbers.
|
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|
||
|
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# Inputs
|
||
|
||
`x`
|
||
|
||
: 1\. Function argument
|
||
|
||
`y`
|
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|
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: 2\. Function argument
|
||
*/
|
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max = x: y: if x > y then x else y;
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|
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/**
|
||
Integer modulus
|
||
|
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|
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# Inputs
|
||
|
||
`base`
|
||
|
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: 1\. Function argument
|
||
|
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`int`
|
||
|
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: 2\. Function argument
|
||
|
||
|
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# Examples
|
||
:::{.example}
|
||
## `lib.trivial.mod` usage example
|
||
|
||
```nix
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mod 11 10
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=> 1
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mod 1 10
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=> 1
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```
|
||
|
||
:::
|
||
*/
|
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mod = base: int: base - (int * (builtins.div base int));
|
||
|
||
|
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## Comparisons
|
||
|
||
/**
|
||
C-style comparisons
|
||
|
||
a < b, compare a b => -1
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a == b, compare a b => 0
|
||
a > b, compare a b => 1
|
||
|
||
|
||
# Inputs
|
||
|
||
`a`
|
||
|
||
: 1\. Function argument
|
||
|
||
`b`
|
||
|
||
: 2\. Function argument
|
||
*/
|
||
compare = a: b:
|
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if a < b
|
||
then -1
|
||
else if a > b
|
||
then 1
|
||
else 0;
|
||
|
||
/**
|
||
Split type into two subtypes by predicate `p`, take all elements
|
||
of the first subtype to be less than all the elements of the
|
||
second subtype, compare elements of a single subtype with `yes`
|
||
and `no` respectively.
|
||
|
||
|
||
# Inputs
|
||
|
||
`p`
|
||
|
||
: Predicate
|
||
|
||
`yes`
|
||
|
||
: Comparison function if predicate holds for both values
|
||
|
||
`no`
|
||
|
||
: Comparison function if predicate holds for neither value
|
||
|
||
`a`
|
||
|
||
: First value to compare
|
||
|
||
`b`
|
||
|
||
: Second value to compare
|
||
|
||
# Type
|
||
|
||
```
|
||
(a -> bool) -> (a -> a -> int) -> (a -> a -> int) -> (a -> a -> int)
|
||
```
|
||
|
||
# Examples
|
||
:::{.example}
|
||
## `lib.trivial.splitByAndCompare` usage example
|
||
|
||
```nix
|
||
let cmp = splitByAndCompare (hasPrefix "foo") compare compare; in
|
||
|
||
cmp "a" "z" => -1
|
||
cmp "fooa" "fooz" => -1
|
||
|
||
cmp "f" "a" => 1
|
||
cmp "fooa" "a" => -1
|
||
# while
|
||
compare "fooa" "a" => 1
|
||
```
|
||
|
||
:::
|
||
*/
|
||
splitByAndCompare =
|
||
p: yes: no: a: b:
|
||
if p a
|
||
then if p b then yes a b else -1
|
||
else if p b then 1 else no a b;
|
||
|
||
|
||
/**
|
||
Reads a JSON file.
|
||
|
||
|
||
# Inputs
|
||
|
||
`path`
|
||
|
||
: 1\. Function argument
|
||
|
||
# Type
|
||
|
||
```
|
||
importJSON :: path -> any
|
||
```
|
||
*/
|
||
importJSON = path:
|
||
builtins.fromJSON (builtins.readFile path);
|
||
|
||
/**
|
||
Reads a TOML file.
|
||
|
||
|
||
# Inputs
|
||
|
||
`path`
|
||
|
||
: 1\. Function argument
|
||
|
||
# Type
|
||
|
||
```
|
||
importTOML :: path -> any
|
||
```
|
||
*/
|
||
importTOML = path:
|
||
builtins.fromTOML (builtins.readFile path);
|
||
|
||
## Warnings
|
||
|
||
# See https://github.com/NixOS/nix/issues/749. Eventually we'd like these
|
||
# to expand to Nix builtins that carry metadata so that Nix can filter out
|
||
# the INFO messages without parsing the message string.
|
||
#
|
||
# Usage:
|
||
# {
|
||
# foo = lib.warn "foo is deprecated" oldFoo;
|
||
# bar = lib.warnIf (bar == "") "Empty bar is deprecated" bar;
|
||
# }
|
||
#
|
||
# TODO: figure out a clever way to integrate location information from
|
||
# something like __unsafeGetAttrPos.
|
||
|
||
/**
|
||
Print a warning before returning the second argument. This function behaves
|
||
like `builtins.trace`, but requires a string message and formats it as a
|
||
warning, including the `warning: ` prefix.
|
||
|
||
To get a call stack trace and abort evaluation, set the environment variable
|
||
`NIX_ABORT_ON_WARN=true` and set the Nix options `--option pure-eval false --show-trace`
|
||
|
||
# Inputs
|
||
|
||
`msg`
|
||
|
||
: Warning message to print.
|
||
|
||
`val`
|
||
|
||
: Value to return as-is.
|
||
|
||
# Type
|
||
|
||
```
|
||
string -> a -> a
|
||
```
|
||
*/
|
||
warn =
|
||
if lib.elem (builtins.getEnv "NIX_ABORT_ON_WARN") ["1" "true" "yes"]
|
||
then msg: builtins.trace "[1;31mwarning: ${msg}[0m" (abort "NIX_ABORT_ON_WARN=true; warnings are treated as unrecoverable errors.")
|
||
else msg: builtins.trace "[1;31mwarning: ${msg}[0m";
|
||
|
||
/**
|
||
Like warn, but only warn when the first argument is `true`.
|
||
|
||
|
||
# Inputs
|
||
|
||
`cond`
|
||
|
||
: 1\. Function argument
|
||
|
||
`msg`
|
||
|
||
: 2\. Function argument
|
||
|
||
`val`
|
||
|
||
: Value to return as-is.
|
||
|
||
# Type
|
||
|
||
```
|
||
bool -> string -> a -> a
|
||
```
|
||
*/
|
||
warnIf = cond: msg: if cond then warn msg else x: x;
|
||
|
||
/**
|
||
Like warnIf, but negated (warn if the first argument is `false`).
|
||
|
||
|
||
# Inputs
|
||
|
||
`cond`
|
||
|
||
: 1\. Function argument
|
||
|
||
`msg`
|
||
|
||
: 2\. Function argument
|
||
|
||
`val`
|
||
|
||
: Value to return as-is.
|
||
|
||
# Type
|
||
|
||
```
|
||
bool -> string -> a -> a
|
||
```
|
||
*/
|
||
warnIfNot = cond: msg: if cond then x: x else warn msg;
|
||
|
||
/**
|
||
Like the `assert b; e` expression, but with a custom error message and
|
||
without the semicolon.
|
||
|
||
If true, return the identity function, `r: r`.
|
||
|
||
If false, throw the error message.
|
||
|
||
Calls can be juxtaposed using function application, as `(r: r) a = a`, so
|
||
`(r: r) (r: r) a = a`, and so forth.
|
||
|
||
|
||
# Inputs
|
||
|
||
`cond`
|
||
|
||
: 1\. Function argument
|
||
|
||
`msg`
|
||
|
||
: 2\. Function argument
|
||
|
||
# Type
|
||
|
||
```
|
||
bool -> string -> a -> a
|
||
```
|
||
|
||
# Examples
|
||
:::{.example}
|
||
## `lib.trivial.throwIfNot` usage example
|
||
|
||
```nix
|
||
throwIfNot (lib.isList overlays) "The overlays argument to nixpkgs must be a list."
|
||
lib.foldr (x: throwIfNot (lib.isFunction x) "All overlays passed to nixpkgs must be functions.") (r: r) overlays
|
||
pkgs
|
||
```
|
||
|
||
:::
|
||
*/
|
||
throwIfNot = cond: msg: if cond then x: x else throw msg;
|
||
|
||
/**
|
||
Like throwIfNot, but negated (throw if the first argument is `true`).
|
||
|
||
|
||
# Inputs
|
||
|
||
`cond`
|
||
|
||
: 1\. Function argument
|
||
|
||
`msg`
|
||
|
||
: 2\. Function argument
|
||
|
||
# Type
|
||
|
||
```
|
||
bool -> string -> a -> a
|
||
```
|
||
*/
|
||
throwIf = cond: msg: if cond then throw msg else x: x;
|
||
|
||
/**
|
||
Check if the elements in a list are valid values from a enum, returning the identity function, or throwing an error message otherwise.
|
||
|
||
|
||
# Inputs
|
||
|
||
`msg`
|
||
|
||
: 1\. Function argument
|
||
|
||
`valid`
|
||
|
||
: 2\. Function argument
|
||
|
||
`given`
|
||
|
||
: 3\. Function argument
|
||
|
||
# Type
|
||
|
||
```
|
||
String -> List ComparableVal -> List ComparableVal -> a -> a
|
||
```
|
||
|
||
# Examples
|
||
:::{.example}
|
||
## `lib.trivial.checkListOfEnum` usage example
|
||
|
||
```nix
|
||
let colorVariants = ["bright" "dark" "black"]
|
||
in checkListOfEnum "color variants" [ "standard" "light" "dark" ] colorVariants;
|
||
=>
|
||
error: color variants: bright, black unexpected; valid ones: standard, light, dark
|
||
```
|
||
|
||
:::
|
||
*/
|
||
checkListOfEnum = msg: valid: given:
|
||
let
|
||
unexpected = lib.subtractLists valid given;
|
||
in
|
||
lib.throwIfNot (unexpected == [])
|
||
"${msg}: ${builtins.concatStringsSep ", " (builtins.map builtins.toString unexpected)} unexpected; valid ones: ${builtins.concatStringsSep ", " (builtins.map builtins.toString valid)}";
|
||
|
||
info = msg: builtins.trace "INFO: ${msg}";
|
||
|
||
showWarnings = warnings: res: lib.foldr (w: x: warn w x) res warnings;
|
||
|
||
## Function annotations
|
||
|
||
/**
|
||
Add metadata about expected function arguments to a function.
|
||
The metadata should match the format given by
|
||
builtins.functionArgs, i.e. a set from expected argument to a bool
|
||
representing whether that argument has a default or not.
|
||
setFunctionArgs : (a → b) → Map String Bool → (a → b)
|
||
|
||
This function is necessary because you can't dynamically create a
|
||
function of the { a, b ? foo, ... }: format, but some facilities
|
||
like callPackage expect to be able to query expected arguments.
|
||
|
||
|
||
# Inputs
|
||
|
||
`f`
|
||
|
||
: 1\. Function argument
|
||
|
||
`args`
|
||
|
||
: 2\. Function argument
|
||
*/
|
||
setFunctionArgs = f: args:
|
||
{ # TODO: Should we add call-time "type" checking like built in?
|
||
__functor = self: f;
|
||
__functionArgs = args;
|
||
};
|
||
|
||
/**
|
||
Extract the expected function arguments from a function.
|
||
This works both with nix-native { a, b ? foo, ... }: style
|
||
functions and functions with args set with 'setFunctionArgs'. It
|
||
has the same return type and semantics as builtins.functionArgs.
|
||
setFunctionArgs : (a → b) → Map String Bool.
|
||
|
||
|
||
# Inputs
|
||
|
||
`f`
|
||
|
||
: 1\. Function argument
|
||
*/
|
||
functionArgs = f:
|
||
if f ? __functor
|
||
then f.__functionArgs or (functionArgs (f.__functor f))
|
||
else builtins.functionArgs f;
|
||
|
||
/**
|
||
Check whether something is a function or something
|
||
annotated with function args.
|
||
|
||
|
||
# Inputs
|
||
|
||
`f`
|
||
|
||
: 1\. Function argument
|
||
*/
|
||
isFunction = f: builtins.isFunction f ||
|
||
(f ? __functor && isFunction (f.__functor f));
|
||
|
||
/**
|
||
`mirrorFunctionArgs f g` creates a new function `g'` with the same behavior as `g` (`g' x == g x`)
|
||
but its function arguments mirroring `f` (`lib.functionArgs g' == lib.functionArgs f`).
|
||
|
||
|
||
# Inputs
|
||
|
||
`f`
|
||
|
||
: Function to provide the argument metadata
|
||
|
||
`g`
|
||
|
||
: Function to set the argument metadata to
|
||
|
||
# Type
|
||
|
||
```
|
||
mirrorFunctionArgs :: (a -> b) -> (a -> c) -> (a -> c)
|
||
```
|
||
|
||
# Examples
|
||
:::{.example}
|
||
## `lib.trivial.mirrorFunctionArgs` usage example
|
||
|
||
```nix
|
||
addab = {a, b}: a + b
|
||
addab { a = 2; b = 4; }
|
||
=> 6
|
||
lib.functionArgs addab
|
||
=> { a = false; b = false; }
|
||
addab1 = attrs: addab attrs + 1
|
||
addab1 { a = 2; b = 4; }
|
||
=> 7
|
||
lib.functionArgs addab1
|
||
=> { }
|
||
addab1' = lib.mirrorFunctionArgs addab addab1
|
||
addab1' { a = 2; b = 4; }
|
||
=> 7
|
||
lib.functionArgs addab1'
|
||
=> { a = false; b = false; }
|
||
```
|
||
|
||
:::
|
||
*/
|
||
mirrorFunctionArgs =
|
||
f:
|
||
let
|
||
fArgs = functionArgs f;
|
||
in
|
||
g:
|
||
setFunctionArgs g fArgs;
|
||
|
||
/**
|
||
Turns any non-callable values into constant functions.
|
||
Returns callable values as is.
|
||
|
||
|
||
# Inputs
|
||
|
||
`v`
|
||
|
||
: Any value
|
||
|
||
|
||
# Examples
|
||
:::{.example}
|
||
## `lib.trivial.toFunction` usage example
|
||
|
||
```nix
|
||
nix-repl> lib.toFunction 1 2
|
||
1
|
||
|
||
nix-repl> lib.toFunction (x: x + 1) 2
|
||
3
|
||
```
|
||
|
||
:::
|
||
*/
|
||
toFunction =
|
||
v:
|
||
if isFunction v
|
||
then v
|
||
else k: v;
|
||
|
||
/**
|
||
Convert the given positive integer to a string of its hexadecimal
|
||
representation. For example:
|
||
|
||
toHexString 0 => "0"
|
||
|
||
toHexString 16 => "10"
|
||
|
||
toHexString 250 => "FA"
|
||
*/
|
||
toHexString = let
|
||
hexDigits = {
|
||
"10" = "A";
|
||
"11" = "B";
|
||
"12" = "C";
|
||
"13" = "D";
|
||
"14" = "E";
|
||
"15" = "F";
|
||
};
|
||
toHexDigit = d:
|
||
if d < 10
|
||
then toString d
|
||
else hexDigits.${toString d};
|
||
in i: lib.concatMapStrings toHexDigit (toBaseDigits 16 i);
|
||
|
||
/**
|
||
`toBaseDigits base i` converts the positive integer i to a list of its
|
||
digits in the given base. For example:
|
||
|
||
toBaseDigits 10 123 => [ 1 2 3 ]
|
||
|
||
toBaseDigits 2 6 => [ 1 1 0 ]
|
||
|
||
toBaseDigits 16 250 => [ 15 10 ]
|
||
|
||
|
||
# Inputs
|
||
|
||
`base`
|
||
|
||
: 1\. Function argument
|
||
|
||
`i`
|
||
|
||
: 2\. Function argument
|
||
*/
|
||
toBaseDigits = base: i:
|
||
let
|
||
go = i:
|
||
if i < base
|
||
then [i]
|
||
else
|
||
let
|
||
r = i - ((i / base) * base);
|
||
q = (i - r) / base;
|
||
in
|
||
[r] ++ go q;
|
||
in
|
||
assert (isInt base);
|
||
assert (isInt i);
|
||
assert (base >= 2);
|
||
assert (i >= 0);
|
||
lib.reverseList (go i);
|
||
}
|