improve heuristic for detecting if curried (#36)

* improve heuristic for detecting if curried

This adds a check that ensures it is either a native function or an
attribute set that only has __functor and/or __functionArgs attributes

* add tests for provides with functors

Author: musjj

checkmate/modules/tests/aspect_provides_functor.nix

@@ -0,0 +1,33 @@
+{
+  mkFlake,
+  evalMod,
+  ...
+}:
+{
+
+  flake.tests."test provides with functors" =
+    let
+      flake = mkFlake {
+        flake.aspects =
+          { aspects, ... }:
+          {
+            aspectOne = {
+              includes = [ aspects.aspectTwo._.aspectThree._.aspectFour ];
+              classOne = { };
+            };
+            aspectTwo.provides.aspectThree = {
+              provides.aspectFour.classOne.bar = [ "hello" ];
+              __functor = self: _: self;
+            };
+          };
+      };
+
+      expr = (evalMod "classOne" flake.modules.classOne.aspectOne).bar;
+      expected = [
+        "hello"
+      ];
+    in
+    builtins.trace expr {
+      inherit expr expected;
+    };
+}

nix/types.nix

@@ -46,7 +46,11 @@ let
   directProviderFn = lib.types.addCheck (lib.types.functionTo aspectSubmodule) isProviderFn;
 
   # Curried provider function: (params) → provider (enables parametrization)
-  curriedProviderFn = lib.types.functionTo providerType;
+  curriedProviderFn = lib.types.addCheck (lib.types.functionTo providerType) (
+    f:
+    builtins.isFunction f
+    || lib.isAttrs f && lib.subtractLists [ "__functor" "__functionArgs" ] (lib.attrNames f) == [ ]
+  );
 
   # Any provider function: direct or curried
   providerFn = lib.types.either directProviderFn curriedProviderFn;