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https://github.com/leventerkok/sbvplugin

Formally prove properties of Haskell programs using SBV/SMT.
https://github.com/leventerkok/sbvplugin

haskell sbv smt verification

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Formally prove properties of Haskell programs using SBV/SMT.

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README 

        
## SBVPlugin: SBV Plugin for GHC



On Hackage: http://hackage.haskell.org/package/sbvPlugin



### Example



```haskell

{-# OPTIONS_GHC -fplugin=Data.SBV.Plugin #-}



module Test where



import Data.SBV.Plugin



test :: Proved (Integer -> Integer -> Bool)

test x y = x + y >= x - y

```



*Note the GHC option on the very first line. Either add this to your file, or pass `-fplugin=Data.SBV.Plugin` as an

argument to GHC, either on the command line or via cabal. Same trick also works for GHCi.*



The `Proved` type simply wraps over the type of the predicate you are trying to prove, typically a function

returning a `Bool` value. It tells the plugin to treat the input as a theorem that needs to be proved.

When compiled, we get:



```

$ ghc -c Test.hs



[SBV] Test.hs:8:1-4 Proving "test", using Z3.

[Z3] Falsifiable. Counter-example:

  x =  0 :: Integer

  y = -1 :: Integer

[SBV] Failed. (Use option 'IgnoreFailure' to continue.)

```



Note that the compilation will be aborted, since the theorem doesn't hold. If you load this file in GHCi, it will simply

fail and drop you back to the GHCi prompt.



### Annotation style

While the `Proved` type should suffice for simple uses, the plugin takes a number of arguments to modify

options and pick underlying solvers. In this case, an explicit annotation can be provided:



```haskell

{-# OPTIONS_GHC -fplugin=Data.SBV.Plugin #-}



module Test where



import Data.SBV.Plugin



{-# ANN test theorem {options = [IgnoreFailure]} #-}

test :: Integer -> Integer -> Bool

test x y = x == y -- clearly not True!

```



The above, for instance, tells the plugin to ignore failed proofs (`IgnoreFailure`). This is useful when you

have a failing theorem that you are still working on, to make sure GHC continues compilation instead of stopping

compilation and erroring out at that point.



### Available options



The plugin currently understands the following options. Multiple options can be given at the same time 

by comma separating them.



```haskell

data SBVOption =

   IgnoreFailure  -- ^ Continue even if proof fails

 | Skip String    -- ^ Skip the proof. Can be handy for properties that we currently do not want to focus on.

 | Verbose        -- ^ Produce verbose output, good for debugging

 | Debug          -- ^ Produce really verbose output, use only when things go really wrong!

 | QuickCheck     -- ^ Perform quickCheck

 | Uninterpret    -- ^ Uninterpret this binding for proof purposes

 | Names [String] -- ^ Use these names for the arguments; need not be exhaustive

 | ListSize Int   -- ^ If a list-input is found, use this length. If not specified, we will complain!

 | Z3             -- ^ Use Z3

 | Yices          -- ^ Use Yices

 | Boolector      -- ^ Use Boolector

 | CVC4           -- ^ Use CVC4

 | MathSAT        -- ^ Use MathSAT

 | ABC            -- ^ Use ABC

 | AnySolver      -- ^ Run all installed solvers in parallel, and report the result from the first to finish

```



### Using SBVPlugin from GHCi

The plugin should work from GHCi with no changes.  Note that when run from GHCi, the plugin will

behave as if the `IgnoreFailure` argument is given on all annotations, so that failures do not stop

the load process.



### Thanks

The following people reported bugs, provided comments/feedback, or contributed to the development of SBVPlugin in

various ways: Nickolas Fotopoulos and Stephan Renatus.