feat(lib.types.linkable): type for "ln -s ${v} $out/mylink" (#545)

Author: BirdeeHub

lib/types.nix

@@ -366,6 +366,31 @@ in
       if builtins.isPath res then builtins.path { path = res; } else res;
   };
 
+  /**
+    Allows values that are, or resolve to under interpolation, an absolute-path-like value.
+
+    A value is considered linkable if it matches any of the following:
+    - It is a Nix store path (e.g. `./.`, `"${./.}"` or a derivation)
+    - It is a plain string that starts with `"/"` and does not contain any newlines
+
+    This is useful when wrapping commands that accept file or directory paths,
+    where you need to distinguish path-like values from other strings.
+
+    For example, when you feel like you want `lib.types.either wlib.types.stringable lib.types.lines`
+
+    You should instead use `lib.types.either wlib.types.linkable lib.types.lines`
+  */
+  linkable = lib.mkOptionType {
+    name = "linkable";
+    descriptionClass = "noun";
+    description = "absolute path";
+    inherit (wlib.types.stringable) merge;
+    check =
+      x:
+      lib.isStringLike x
+      && (if builtins.isString x then builtins.substring 0 1 x == "/" && !lib.hasInfix "\n" x else true);
+  };
+
   /**
     A single-line, non-empty string
   */

wrapperModules/t/television/module.nix

@@ -11,12 +11,7 @@ let
     nullable = false;
     typeName = "TOML";
   };
-  isPathLike =
-    x:
-    builtins.isPath x
-    || (lib.isStringLike x && !builtins.isString x)
-    || (builtins.isString x && lib.hasPrefix "/" x)
-    || lib.isStorePath x;
+  isLinkable = wlib.types.linkable.check;
 in
 {
   imports = [ wlib.modules.default ];
@@ -27,7 +22,7 @@ in
       description = "Television configuration options.";
     };
     channels = lib.mkOption {
-      type = types.lazyAttrsOf (types.either wlib.types.stringable tomlFmtType);
+      type = types.lazyAttrsOf (types.either wlib.types.linkable tomlFmtType);
       default = { };
       description = "Television channels to install.";
     };
@@ -40,7 +35,7 @@ in
       '';
     };
     themes = lib.mkOption {
-      type = types.lazyAttrsOf (types.either wlib.types.stringable tomlFmtType);
+      type = types.lazyAttrsOf (types.either wlib.types.linkable tomlFmtType);
       default = { };
       description = "Themes of television to install.";
     };
@@ -84,17 +79,17 @@ in
       key = "channel_${n}";
       relPath = lib.mkOverride 0 "${config.binName}-channels/${n}.toml";
       output = lib.mkOverride 0 config.configDrvOutput;
-      ${if isPathLike v then null else "content"} = builtins.toJSON v;
+      ${if isLinkable v then null else "content"} = builtins.toJSON v;
       "builder" =
-        if isPathLike v then ''ln -s ${v} "$2"'' else ''${pkgs.remarshal}/bin/json2toml "$1" "$2"'';
+        if isLinkable v then ''ln -s ${v} "$2"'' else ''${pkgs.remarshal}/bin/json2toml "$1" "$2"'';
     }) config.channels
     // builtins.mapAttrs (n: v: {
       key = "theme_${n}";
       relPath = lib.mkOverride 0 "${config.binName}-themes/${n}.toml";
       output = lib.mkOverride 0 config.configDrvOutput;
-      ${if isPathLike v then null else "content"} = builtins.toJSON v;
+      ${if isLinkable v then null else "content"} = builtins.toJSON v;
       "builder" =
-        if isPathLike v then ''ln -s ${v} "$2"'' else ''${pkgs.remarshal}/bin/json2toml "$1" "$2"'';
+        if isLinkable v then ''ln -s ${v} "$2"'' else ''${pkgs.remarshal}/bin/json2toml "$1" "$2"'';
     }) config.themes;
     meta.maintainers = [ wlib.maintainers.allen-liaoo ];
   };