Split annotationLabel and extensionLabel (#20)

* Split `annotationLabel` and `extensionLabel`
* Add example

Author: andy-morris

examples/reused-name/ReusedName.hs

@@ -0,0 +1,9 @@
+import ReusedNameBase
+
+extendA "A" [] [t|Int|] $
+  defaultExtA {
+    typeAX = [("B", [("y", [t|String|])])]
+  }
+
+main :: IO ()
+main = pure ()

examples/reused-name/ReusedNameBase.hs

@@ -0,0 +1,4 @@
+module ReusedNameBase where
+import Extensible
+
+extensible [d| data A = A {x :: Int} |]

extensible-data.cabal

@@ -106,6 +106,12 @@ executable generic
   hs-source-dirs: examples/generic
   main-is: Generic.hs
 
+executable reused-name
+  import: deps, example
+  hs-source-dirs: examples/reused-name
+  main-is: ReusedName.hs
+  other-modules: ReusedNameBase
+
 executable lam
   import: deps, example
   hs-source-dirs: examples/lam

src/Extensible.hs

@@ -352,11 +352,14 @@ data Config = Config {
     bundleName :: NameAffix,
     -- | Appled to constructor names to get the annotation type family's name
     annotationName :: NameAffix,
+    -- | If extending a record constructor, apply this to the constructor name
+    -- to get the annotation field's label.
+    annotationLabel :: NameAffix,
     -- | Applied to datatype name to get extension constructor & type family's
     -- name
     extensionName :: NameAffix,
-    -- | If extending a record constructor, apply this to the constructor name
-    -- to get the extension field's label.
+    -- | If the extending constructor is a record, apply this to the constructor
+    -- name to get the extension field's label.
     extensionLabel :: NameAffix,
     -- | Applied to datatype name to get extension record name
     extRecordName :: NameAffix,
@@ -384,6 +387,7 @@ data Config = Config {
 --   constructorName = NameSuffix \"'\",
 --   bundleName      = NameSuffix \"All\",
 --   annotationName  = NamePrefix \"X\",
+--   annotationLabel = NamePrefix \"ann\",
 --   extensionName   = NameSuffix \"X\",
 --   extensionLabel  = NamePrefix \"ext\",
 --   extRecordName   = NamePrefix \"Ext\",
@@ -400,6 +404,7 @@ defaultConfig = Config {
     constructorName = NameSuffix "'",
     bundleName      = NameSuffix "All",
     annotationName  = NamePrefix "X",
+    annotationLabel = NamePrefix "ann",
     extensionName   = NameSuffix "X",
     extensionLabel  = NamePrefix "ext",
     extRecordName   = NamePrefix "Ext",
@@ -570,7 +575,7 @@ extendCon conf nameMap ext tvs (SimpleCon name fields) = do
   case fields' of
     NormalFields fs -> pure $ NormalC name' $ fs ++ [(strict, extField)]
     RecFields fs ->
-      let extLabel = applyAffix (extensionLabel conf) name in
+      let extLabel = applyAffix (annotationLabel conf) name in
       pure $ RecC name' $ fs ++ [(extLabel, strict, extField)]
 
 -- | Replaces recursive occurences of the datatype with the new one.