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18520b7f36
They are cut off after a few decimal places; we cannot in good faith define a default string representation with that.
230 lines
7.6 KiB
Nix
230 lines
7.6 KiB
Nix
/* Functions that generate widespread file
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* formats from nix data structures.
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*
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* They all follow a similar interface:
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* generator { config-attrs } data
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*
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* `config-attrs` are “holes” in the generators
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* with sensible default implementations that
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* can be overwritten. The default implementations
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* are mostly generators themselves, called with
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* their respective default values; they can be reused.
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*
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* Tests can be found in ./tests.nix
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* Documentation in the manual, #sec-generators
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*/
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{ lib }:
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with (lib).trivial;
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let
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libStr = lib.strings;
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libAttr = lib.attrsets;
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inherit (lib) isFunction;
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in
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rec {
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## -- HELPER FUNCTIONS & DEFAULTS --
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/* Convert a value to a sensible default string representation.
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* The builtin `toString` function has some strange defaults,
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* suitable for bash scripts but not much else.
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*/
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mkValueStringDefault = {}: v: with builtins;
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let err = t: v: abort
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("generators.mkValueStringDefault: " +
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"${t} not supported: ${toPretty {} v}");
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in if isInt v then toString v
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# we default to not quoting strings
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else if isString v then v
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# isString returns "1", which is not a good default
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else if true == v then "true"
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# here it returns to "", which is even less of a good default
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else if false == v then "false"
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else if null == v then "null"
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# if you have lists you probably want to replace this
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else if isList v then err "lists" v
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# same as for lists, might want to replace
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else if isAttrs v then err "attrsets" v
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# functions can’t be printed of course
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else if isFunction v then err "functions" v
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# let’s not talk about floats. There is no sensible `toString` for them.
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else if isFloat v then err "floats" v
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else err "this value is" (toString v);
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/* Generate a line of key k and value v, separated by
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* character sep. If sep appears in k, it is escaped.
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* Helper for synaxes with different separators.
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*
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* mkValueString specifies how values should be formatted.
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*
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* mkKeyValueDefault {} ":" "f:oo" "bar"
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* > "f\:oo:bar"
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*/
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mkKeyValueDefault = {
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mkValueString ? mkValueStringDefault {}
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}: sep: k: v:
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"${libStr.escape [sep] k}${sep}${mkValueString v}";
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## -- FILE FORMAT GENERATORS --
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/* Generate a key-value-style config file from an attrset.
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*
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* mkKeyValue is the same as in toINI.
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*/
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toKeyValue = {
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mkKeyValue ? mkKeyValueDefault {} "="
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}: attrs:
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let mkLine = k: v: mkKeyValue k v + "\n";
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in libStr.concatStrings (libAttr.mapAttrsToList mkLine attrs);
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/* Generate an INI-style config file from an
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* attrset of sections to an attrset of key-value pairs.
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*
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* generators.toINI {} {
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* foo = { hi = "${pkgs.hello}"; ciao = "bar"; };
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* baz = { "also, integers" = 42; };
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* }
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*
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*> [baz]
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*> also, integers=42
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*>
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*> [foo]
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*> ciao=bar
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*> hi=/nix/store/y93qql1p5ggfnaqjjqhxcw0vqw95rlz0-hello-2.10
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*
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* The mk* configuration attributes can generically change
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* the way sections and key-value strings are generated.
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*
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* For more examples see the test cases in ./tests.nix.
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*/
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toINI = {
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# apply transformations (e.g. escapes) to section names
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mkSectionName ? (name: libStr.escape [ "[" "]" ] name),
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# format a setting line from key and value
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mkKeyValue ? mkKeyValueDefault {} "="
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}: attrsOfAttrs:
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let
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# map function to string for each key val
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mapAttrsToStringsSep = sep: mapFn: attrs:
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libStr.concatStringsSep sep
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(libAttr.mapAttrsToList mapFn attrs);
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mkSection = sectName: sectValues: ''
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[${mkSectionName sectName}]
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'' + toKeyValue { inherit mkKeyValue; } sectValues;
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in
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# map input to ini sections
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mapAttrsToStringsSep "\n" mkSection attrsOfAttrs;
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/* Generates JSON from an arbitrary (non-function) value.
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* For more information see the documentation of the builtin.
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*/
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toJSON = {}: builtins.toJSON;
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/* YAML has been a strict superset of JSON since 1.2, so we
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* use toJSON. Before it only had a few differences referring
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* to implicit typing rules, so it should work with older
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* parsers as well.
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*/
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toYAML = {}@args: toJSON args;
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/* Pretty print a value, akin to `builtins.trace`.
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* Should probably be a builtin as well.
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*/
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toPretty = {
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/* If this option is true, attrsets like { __pretty = fn; val = …; }
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will use fn to convert val to a pretty printed representation.
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(This means fn is type Val -> String.) */
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allowPrettyValues ? false
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}@args: v: with builtins;
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let isPath = v: typeOf v == "path";
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in if isInt v then toString v
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else if isFloat v then "~${toString v}"
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else if isString v then ''"${libStr.escape [''"''] v}"''
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else if true == v then "true"
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else if false == v then "false"
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else if null == v then "null"
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else if isPath v then toString v
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else if isList v then "[ "
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+ libStr.concatMapStringsSep " " (toPretty args) v
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+ " ]"
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else if isAttrs v then
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# apply pretty values if allowed
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if attrNames v == [ "__pretty" "val" ] && allowPrettyValues
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then v.__pretty v.val
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# TODO: there is probably a better representation?
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else if v ? type && v.type == "derivation" then
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"<δ:${v.name}>"
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# "<δ:${concatStringsSep "," (builtins.attrNames v)}>"
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else "{ "
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+ libStr.concatStringsSep " " (libAttr.mapAttrsToList
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(name: value:
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"${toPretty args name} = ${toPretty args value};") v)
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+ " }"
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else if isFunction v then
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let fna = lib.functionArgs v;
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showFnas = concatStringsSep "," (libAttr.mapAttrsToList
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(name: hasDefVal: if hasDefVal then "(${name})" else name)
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fna);
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in if fna == {} then "<λ>"
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else "<λ:{${showFnas}}>"
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else abort "generators.toPretty: should never happen (v = ${v})";
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# PLIST handling
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toPlist = {}: v: let
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isFloat = builtins.isFloat or (x: false);
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expr = ind: x: with builtins;
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if x == null then "" else
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if isBool x then bool ind x else
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if isInt x then int ind x else
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if isString x then str ind x else
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if isList x then list ind x else
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if isAttrs x then attrs ind x else
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if isFloat x then float ind x else
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abort "generators.toPlist: should never happen (v = ${v})";
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literal = ind: x: ind + x;
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bool = ind: x: literal ind (if x then "<true/>" else "<false/>");
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int = ind: x: literal ind "<integer>${toString x}</integer>";
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str = ind: x: literal ind "<string>${x}</string>";
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key = ind: x: literal ind "<key>${x}</key>";
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float = ind: x: literal ind "<real>${toString x}</real>";
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indent = ind: expr "\t${ind}";
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item = ind: libStr.concatMapStringsSep "\n" (indent ind);
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list = ind: x: libStr.concatStringsSep "\n" [
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(literal ind "<array>")
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(item ind x)
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(literal ind "</array>")
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];
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attrs = ind: x: libStr.concatStringsSep "\n" [
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(literal ind "<dict>")
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(attr ind x)
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(literal ind "</dict>")
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];
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attr = let attrFilter = name: value: name != "_module" && value != null;
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in ind: x: libStr.concatStringsSep "\n" (lib.flatten (lib.mapAttrsToList
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(name: value: lib.optional (attrFilter name value) [
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(key "\t${ind}" name)
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(expr "\t${ind}" value)
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]) x));
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in ''<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE plist PUBLIC "-//Apple Computer//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
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<plist version="1.0">
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${expr "" v}
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</plist>'';
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}
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