Add a function to extract the annotation from a SplitDiff.

src/SplitDiff.hs

@@ -1,6 +1,7 @@
 module SplitDiff where
 
 import Control.Monad.Free (Free(..))
+import Data.Copointed (copoint)
 import Diff (Annotated(..))
 import Term (Term)
 
@@ -16,3 +17,8 @@ getSplitTerm (SplitReplace a) = a
 
 -- | A diff with only one side’s annotations.
 type SplitDiff leaf annotation = Free (Annotated leaf annotation) (SplitPatch (Term leaf annotation))
+
+-- | Get the Info from a split diff
+getSplitAnnotation :: SplitDiff leaf annotation -> annotation
+getSplitAnnotation (Pure patch) = copoint (getSplitTerm patch)
+getSplitAnnotation (Free annotated) = annotation annotated