Initial commit

flake/den/templates/default/modules/aspects/eg/routes.nix

@@ -0,0 +1,37 @@
+# This example implements an aspect "routing" pattern.
+#
+# Unlike `den.default` which is `parametric.atLeast`
+# we use `parametric.fixedTo` here, which help us
+# propagate an already computed context to all includes.
+#
+# This aspect, when installed in a `parametric.atLeast`
+# will just forward the same context.
+# The `mutual` helper returns an static configuration which
+# is ignored by parametric aspects, thus allowing
+# non-existing aspects to be just ignored.
+#
+# Be sure to read: https://vic.github.io/den/dependencies.html
+# See usage at: defaults.nix, alice.nix, igloo.nix
+#
+{ den, eg, ... }:
+{
+  # Usage: `den.default.includes [ eg.routes ]`
+  eg.routes =
+    let
+      inherit (den.lib) parametric;
+
+      # eg, `<user>._.<host>` and `<host>._.<user>`
+      mutual = from: to: den.aspects.${from.aspect}._.${to.aspect} or { };
+
+      routes =
+        { host, user, ... }@ctx:
+        {
+          __functor = parametric.fixedTo ctx;
+          includes = [
+            (mutual user host)
+            (mutual host user)
+          ];
+        };
+    in
+    routes;
+}