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lib/lazyloader: [BROKEN] Introduce lazyloader
Implement functionality that lazily loads modules (by ab)using the `freeformType` option"
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‎modules/deprecated.nix‎

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{
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}

‎modules/hjem.nix‎

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rumLib,
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inputs,
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}: {
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config,
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options,
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...
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}: let
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resolvedConfig =
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rumLib.modules.resolveModulesFromLazyModule {
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modulesDir = ./collection;
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deferredModule = config.rum;
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extraModules = [
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inputs.hjem.nixosModules.hjem-lib
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{_module.args.rumLib = rumLib;}
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(
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{
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config,
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options,
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...
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}: {
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options = options.rum;
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config.rum = builtins.removeAttrs config ["rum"];
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}
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)
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./deprecated.nix
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];
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inherit rumLib options;
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}
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// {
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_module.args.rumLib = rumLib;
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};
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usedConfig = builtins.removeAttrs resolvedConfig ["rum"];
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in {
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# Import the Hjem Rum module collection as an extraModule available under `hjem.users.<username>`
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# This allows the definition of rum modules under `hjem.users.<username>.rum`
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# Import the collection modules recursively so that all files
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# are imported. This then gets imported into the user's
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# 'hjem.extraModules' to make them available under 'hjem.users.<username>'
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imports = [inputs.hjem.nixosModules.hjem-lib] ++ lib.filesystem.listFilesRecursive ./collection;
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options.rum = lib.mkOption {
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type = lib.types.deferredModule;
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default = {};
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};
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_module.args.rumLib = rumLib;
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config = {
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files = usedConfig;
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};
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}

‎modules/lib/black_magic.nix‎

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{lib}: let
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inherit
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(builtins)
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filter
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isAttrs
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isNull
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isString
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concatLists
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head
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readDir
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mapAttrs
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length
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hasAttr
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getAttr
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concatStringsSep
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attrNames
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attrValues
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;
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inherit
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(lib.attrsets)
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mapAttrsToList
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showAttrPath
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attrByPath
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mergeAttrsList
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filterAttrs
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recursiveUpdate
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;
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inherit
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(lib.lists)
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last
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drop
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dropEnd
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fold
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;
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inherit (lib.modules) evalModules;
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/**
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This is effectively (builtins.tail list), however even the docs themselves state
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to avoid that function due to an operation cost of O(n) instead of O(1) per call.
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tail :: [ T ] -> [ T ]
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*/
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tail = list: (drop 1 list);
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/**
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A bit of terminology to prevent possible confusion of myself and others in the future:
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path: An attribute path,
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e.g.
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{ a = { b = "c"; }; } => [ "a" "b" ]
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or
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{ a = { b = mkOption {...}; }; } => [ "a" "b" ]
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filetree:
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Just your regular directory with possibly nested directories.
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filetree != path (in this context)
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Some custom types used throughout the annotations:
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filetree :: { ${pathComponent} :: (filetree | ${file}}) }
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attrPath :: [ string ]
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moduleResolutionResult :: { resolved :: [ ${filepath} ]; unresolved :: [ ${attrPath} ] }
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*/
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resolveFileTreeRecursive = path: let
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dirItems = readDir path;
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in
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mapAttrs (
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name: value: let
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ItemPath = path + ("/" + name);
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in
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if value == "directory"
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then resolveFileTreeRecursive ItemPath
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else ItemPath
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)
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dirItems;
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/**
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pop the last element from the list
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pop :: [ T ] -> [ T ]
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*/
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/**
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If the current attrset is a final value, return an empty path as there are no child paths.
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Else, recurse into each child value, get their paths, add the child name to the path,
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and combine all child paths into one list
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getAttrPaths' :: { ... :: ?; _type ? :: string } -> [ attrPath | [ string | 1 ] ]
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*/
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getAttrPaths' = attrset:
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if !(isAttrs attrset) || (attrset ? _type && isString attrset._type)
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then
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if isAttrs attrset && attrset._type == "if"
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then [[1]] # No fucking idea what do do here instead of throwing, I dont think this can happen though.
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else [[]]
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else
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concatLists (
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mapAttrsToList (name: value: map (path: [name] ++ path) (getAttrPaths' value)) attrset
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);
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/**
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getAttrPaths' but with checking
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getAttrPaths :: { ... :: ?; _type ? :: string } -> [ attrPath ]
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*/
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getAttrPaths = set:
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map (
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path:
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if (last path) == 1
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then throw "Encountered mkIf value at ${showAttrPath (dropEnd 1 path)}"
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else path
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) (getAttrPaths' set);
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pathToAttr = path: value:
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if (length path) > 0
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then {"${head path}" = pathToAttr (tail path) value;}
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else value;
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in {
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/**
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Take a deferredModule, and use it to determine what modules need loading
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resolveModulesFromLazyModule :: { modulesDir :: Path; deferredModule :: deferredModule; rumLib :: rumLib; extraModules ? :: [ module ] } -> [ module ]
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*/
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resolveModulesFromLazyModule = {
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modulesDir,
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deferredModule,
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rumLib,
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extraModules ? [],
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options,
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}: let
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moduleFileTree = resolveFileTreeRecursive modulesDir;
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/**
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To collect the paths of files to import we need to do a couple things:
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- ~~Figure out the attrPaths to the bottommost option declarations~~ 6 months later; what does this even mean??? ( 2(?) months after, I still dont know what I was yapping about )
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- Consider mkIf's
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- Make sure to filter (Filter *what* ??????)
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*/
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/**
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Attempt to resolve all used config values without a matching option into filepaths pointing to modules
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resolveLazyModules :: { config :: ?; options :: ? } -> moduleResolutionResult
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*/
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resolveLazyModules = {
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config,
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options,
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...
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}: let
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/**
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All config values that dont have a matching option (?)
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freeformAttrPaths :: [ attrPath ]
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*/
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freeformAttrPaths = filter (
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path: let
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maybeOption = attrByPath path null options;
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in
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!(isAttrs maybeOption && maybeOption ? _type && maybeOption._type == "option")
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) (getAttrPaths config);
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/**
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Recurse into each part of a path and try to resolve it to a file, returning null when unsucessful
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resolvePathToModule' :: attrPath -> { ...: string } -> string | null
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*/
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resolvePathToModule' = path: filetree: let
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headElem = head path;
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in
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if hasAttr headElem filetree
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then let
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subtree = getAttr headElem filetree;
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in
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assert (isAttrs subtree);
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resolvePathToModule' (tail path) subtree
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else let
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fileHeadElem = headElem + ".nix";
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in
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if hasAttr fileHeadElem filetree
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then let
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file = getAttr fileHeadElem filetree;
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in
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assert isString file; file
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else if filetree ? "default.nix"
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then filetree."default.nix"
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else null;
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/**
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Resolve an attrPath to a module file.
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Return format: { "attr.path.seperated.with.dots" = "file/or/null/if/file/doesn't/exist.nix"}
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resolvePathToModule :: attrPath -> { ${attrPath} :: string | null }
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*/
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resolvePathToModule = path: {
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"${concatStringsSep "." path}" = resolvePathToModule' path moduleFileTree;
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};
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/**
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All resolved and unresolved module files
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allModules :: { ${attrPath} :: string | null }
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*/
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allModules = mergeAttrsList (map resolvePathToModule freeformAttrPaths);
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/**
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Get it? because you filter for all items "where Value is [what]". e.g. all items where Value is String
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whereValue :: (? -> bool) -> { ... :: ? } -> { ... :: ? }
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*/
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whereValue = isWhat: filterAttrs (_: isWhat);
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out = {
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resolved = attrValues (whereValue isString allModules);
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unresolved = attrNames (whereValue isNull allModules);
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};
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in
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out;
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/**
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iterate :: [ module ] -> { config :: { ... :: ? }; options :: { ... :: ? } }
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*/
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iterate = resolvedModules:
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evalModules {
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modules =
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resolvedModules
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++ [
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deferredModule
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(
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let
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opts = removeAttrs options ["_module"];
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in {
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_file = "${__curPos.file}:${builtins.toString __curPos.line}";
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options = opts;
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config = {
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_module = {
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freeformType = lib.types.attrs;
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args = {inherit rumLib;};
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};
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};
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}
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)
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];
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};
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/**
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converge :: [ module ] -> moduleResolutionResult -> Int -> { config :: { ... :: ? }; unresolved :: [ string ] }
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*/
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converge = resolvedModules: prevAllModules: limit:
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if limit == 0
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then throw "Module evaluation did not converge after iteration limit"
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else let
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current = iterate prevAllModules.resolved;
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currentAllModules = resolveLazyModules current;
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in
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if (length currentAllModules.resolved) == 0
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then {
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config = current.config;
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inherit (currentAllModules) unresolved;
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} # Converged
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else converge (resolvedModules ++ currentAllModules.resolved) currentAllModules (limit - 1);
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/**
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converged :: { config :: { ... :: ?}; unresolved :: [ string ] }
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*/
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converged = converge extraModules {resolved = [];} 20;
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/**
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config :: { ... :: ? }
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*/
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config =
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if (length converged.unresolved) > 0
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then throw "Hjem-Rum: Couldn't find module(s) matching the following configuration value(s) \n ${converged.unresolved}"
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else converged.config;
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/**
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`config`, filtered to only include values that match non-rum options. (i.e. hjem options)
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Yes, this basically is the same logic as for `freeformAtrrPaths`, except the filter inverted
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finalConfigAttrPaths :: { ... :: ? }
276+
*/
277+
finalConfigAttrPaths = filter (
278+
path: let
279+
maybeOption = attrByPath path null options;
280+
in (isAttrs maybeOption && maybeOption ? _type && maybeOption._type == "option")
281+
) (getAttrPaths config);
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finalConfig = fold recursiveUpdate {} (
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map (path: pathToAttr path (attrByPath path null config)) finalConfigAttrPaths
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);
286+
in
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finalConfig;
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}

‎modules/lib/default.nix‎

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attrsets = import ./attrsets {inherit lib;};
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generators = import ./generators {inherit lib;};
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types = import ./types {inherit lib;};
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modules = import ./black_magic.nix {inherit lib;};
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}

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