From the haddocks API of gdiff-ig it seems that you can’t actually use it for something useful:

http://hackage.haskell.org/package/gdiff-ig-0.1.1 The EditScript type is not exported. Thought someone might want to fix it. There is a test suite using the package: http://hackage.haskell.org/package/gdiff-ig-0.1.1/src/examples/Test.hs But it doesn’t actually inspect EditScript, it just uses its equality instance. You can only use it with patch, but in order to get a EditScript you need both values, so there’s no point in doing let p = diff a b in patch p a, you might as well just use b. And EditScript can’t be serialized. Ciao!