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mithrandi/lenses-monadic.hs

Created January 13, 2015 14:39
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Lenses example with IO
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lenses-monadic.hs
findDataset :: Dataset -> Maybe String
findDataset (view datasetName -> Just name) = M.lookup name datasets
findDataset (view datasetName -> Nothing) = Nothing
update_dataset_id :: Dataset -> IO Dataset
update_dataset_id d =
case findDataset d of
Just did -> return $ d & datasetId ?~ did
Nothing -> (\did -> d & datasetId ?~ did) <$> toString <$> nextRandom
update_all_dataset_ids :: Deployment -> IO Deployment
update_all_dataset_ids = mapMOf (nodes.traversed.applications.traversed.volume.dataset) update_dataset_id
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