----------------------------------------------------------------------------- -- | -- Module : Data.SBV.Examples.Misc.ModelExtract -- Copyright : (c) Levent Erkok -- License : BSD3 -- Maintainer : erkokl@gmail.com -- Stability : experimental -- -- Demonstrates use of programmatic model extraction. When programming with -- SBV, we typically use `sat`/`allSat` calls to compute models automatically. -- In more advanced uses, however, the user might want to use programmable -- extraction features to do fancier programming. We demonstrate some of -- these utilities here. ----------------------------------------------------------------------------- module Data.SBV.Examples.Misc.ModelExtract where import Data.SBV -- | A simple function to generate a new integer value, that is not in the -- given set of values. We also require the value to be non-negative outside :: [Integer] -> IO SatResult outside disallow = sat $ do x <- sInteger "x" let notEq i = constrain $ x ./= literal i mapM_ notEq disallow return $ x .>= 0 -- | We now use "outside" repeatedly to generate 10 integers, such that we not only disallow -- previously generated elements, but also any value that differs from previous solutions -- by less than 5. Here, we use the `getModelValue` function. We could have also extracted the dictionary -- via `getModelDictionary` and did fancier programming as well, as necessary. We have: -- -- >>> genVals -- [45,40,35,30,25,20,15,10,5,0] genVals :: IO [Integer] genVals = go [] [] where go _ model | length model >= 10 = return model go disallow model = do res <- outside disallow -- Look up the value of "x" in the generated model -- Note that we simply get an integer here; but any -- SBV known type would be OK as well. case "x" `getModelValue` res of Just c -> go [c-4 .. c+4] (c : model) _ -> return model