tweak AST traversal

src/Ast.hs

@@ -19,6 +19,7 @@ import           Control.Monad
 import           Data.Data
 import           Data.Generics.Uniplate.Data
 import           Data.List
+import           Data.Maybe
 import qualified GHC
 import           GHC hiding (Module, moduleName)
 import           GHC.Paths (libdir)
@@ -210,4 +211,8 @@ getClassMethodUsedNames ast =
 
 -- | extracts all used names from ASTs
 usedNames :: [Name] -> HsBindLR Name Name -> [Name]
-usedNames ids = filter (`notElem` ids) . universeBi
+usedNames _ids = catMaybes . map extractHsVar . (universeBi :: HsBindLR Name Name -> [HsExpr Name])
+  where
+    extractHsVar :: HsExpr Name -> Maybe Name
+    extractHsVar (HsVar n) = Just n
+    extractHsVar _ = Nothing

test/AstSpec.hs

@@ -61,7 +61,7 @@ spec = do
           |])
       withModules [a, b] $ do
         parseStringGraph ["A.hs", "B.hs"] `shouldReturn`
-          Graph [("A.foo", []), ("B.bar", [])] []
+          Graph [("A.foo", ["A.foo"]), ("B.bar", ["B.bar"])] []
 
     it "does not create any files" $ do
       withFooHeader [i|
@@ -158,11 +158,20 @@ spec = do
           (Just foo) = let x = x in x
         |] $ do
           parseStringGraph ["Foo.hs"] `shouldReturn`
-            Graph [("Foo.foo", ["GHC.Base.Just"])] []
+            Graph [("Foo.foo", [])] []
 
       it "can parse tuple pattern binding" $ do
         withFooHeader [i|
           (a, b) = let x = x in x
         |] $ do
           parseStringGraph ["Foo.hs"] `shouldReturn`
             Graph [("Foo.a", []), ("Foo.b", [])] []
+
+    context "local variables" $ do
+      it "recognizes recursive definitions" $ do
+        withFooHeader [i|
+          foo = foo
+          bar = ()
+        |] $ do
+          parseStringGraph ["Foo.hs"] `shouldReturn`
+            Graph [("Foo.bar", ["GHC.Tuple.()"]), ("Foo.foo", ["Foo.foo"])] []

test/Helper.hs

@@ -21,7 +21,7 @@ withFoo code =
 
 withFooHeader :: String -> IO () -> IO ()
 withFooHeader code =
-  withFoo ("module Foo where\n" ++ code)
+  withFoo ("module Foo where\n" ++ unindent code)
 
 withModules :: [(String, String)] -> IO () -> IO ()
 withModules modules action = do