I think acid-state (http://hackage.haskell.org/package/acid-state) might do what you want, at least in broad strokes. It uses a durable transaction log to store query and update events.
As far as I know, the interface to the library doesn't expose an undo/rollback function, so you'd have a bit of work to do to extend it to your use case. But the core functionality to make it possible should be there. Can you use ghc extensions aside from Template Haskell? Template Haskell you can do without with acid-state, but without GADTs and so on you'll have problems. On Sun, Jan 6, 2013 at 12:01 PM, Casey Basichis <caseybasic...@gmail.com>wrote: > Hi, > > I am still getting a hang of Haskell. Sorry if the answer is obvious. > > What sorts of packages and approaches should I be looking at if I was > looking to store something like an Undo stack into a database. > > Each table would refer to a function. > Each records input and outputs would specify both a table ID and record > ID. > The records would also have a data and a Process ID to associate all > functions to a specific process and give them an order. > > No records are ever deleted. Rolling something back is instead a process > of recreating a new, modified graph by taking the old graph from the > database. > > I should note that while I can generate some of the boiler parts from > template haskell in advance I'm ultimately using a stage 1 compiler with no > GHCI o template haskell. > > Thanks, > Casey > > -- > Casey James Basichis > Composer - Cartoon Network > http://www.caseyjamesbasichis.com > caseybasic...@gmail.com > 310.387.7540 > > _______________________________________________ > Haskell-Cafe mailing list > Haskell-Cafe@haskell.org > http://www.haskell.org/mailman/listinfo/haskell-cafe > >
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