1.0

• Add Unix diff style annotations to output of prettyContextDiff, e.g @@ -1,5 +1,4 @@. This required three changes to the signature of getContextDiff due to the addition of a wrapper type Numbered, which enumerates the elements of the input list.

• Signature change 1: The element pretty printer type changes from (a -> Doc) to (Numbered a -> Doc). An unnumber function is provided so that the old behavior can be obtained by changing that argument from pretty to (pretty . unnumber)

• Signature change 2: The result type of getContextDiff changes from ContextDiff a to ContextDiff (Numbered a). A function unNumberContextDiff is provided to convert the result back to the old type.

• Signature change 3: the context argument is now Maybe Int rather than Int, reflecting the change made to getContextDiffNew in 0.5.

• A prettyContextDiffOld function is provided to get the old style output.

• The old broken version of getContextDiffOld is removed.

• Document the behavior of groupBy'.

0.5

• Bring space complexity down to D^2 (Bodigrim).
• Add Bifunctor instance (Jonathan King). Requires base >= 4.8.
• Fix for the grouped context diff. It was omitting all trailing contexts.
• Allow unlimited number of context elements (getContextDiffNew).

0.4

• Generalize Diff a to PolyDiff a b. Diff has been replaced with a specialized synonym type Diff a = PolyDiff a a, but it's still not backward compatible if you imported Diff(..).