add monoid instance for Kernel to avoid some duplication.

data-default may be prettier instead, since there isn't a canonical
mappend.

Hspec.hs

@@ -7,6 +7,7 @@ import Data.List
 import System.Directory
 import Data.String.Here
 import Data.String.Utils (strip, replace)
+import Data.Monoid
 
 import IHaskell.Eval.Parser
 import IHaskell.Types
@@ -33,7 +34,7 @@ eval string = do
   outputAccum <- newIORef []
   let publish _ displayDatas = modifyIORef outputAccum (displayDatas :)
   getTemporaryDirectory >>= setCurrentDirectory
-  let state = KernelState 1 LintOff
+  let state = mempty :: KernelState
   interpret $ Eval.evaluate state string publish
   out <- readIORef outputAccum
   return $ reverse out

IHaskell/Types.hs

@@ -75,6 +75,13 @@ data KernelState = KernelState
     getCwd :: String
   }
 
+
+-- | like 'First', except also add up the execution counter
+instance Monoid KernelState where
+   mempty = KernelState 1 LintOn "." 
+   KernelState na sa cwda `mappend` KernelState nb sb cwdb = 
+    KernelState (na+nb) sa cwda
+
 -- | Initialization information for the kernel.
 data InitInfo = InitInfo {
   extensions :: [String],   -- ^ Extensions to enable at start.

Main.hs

@@ -260,11 +260,7 @@ runKernel profileSrc initInfo = do
 -- Initial kernel state.
 initialKernelState :: IO (MVar KernelState)
 initialKernelState =
-  newMVar KernelState {
-    getExecutionCounter = 1,
-    getLintStatus = LintOn,
-    getCwd = "."
-  }
+  newMVar mempty
 
 -- | Duplicate a message header, giving it a new UUID and message type.
 dupHeader :: MessageHeader -> MessageType -> IO MessageHeader