Support building against integer-simple

package.yaml

@@ -19,6 +19,13 @@ flags:
     default: false
     manual: true
 
+  integer-simple:
+    description: >-
+      Use the [simple integer library](http://hackage.haskell.org/package/integer-simple)
+      instead of [integer-gmp](http://hackage.haskell.org/package/integer-gmp)
+    default: False
+    manual: False
+
 ghc-options: -Wall -fwarn-tabs -fwarn-incomplete-uni-patterns -fwarn-incomplete-record-updates -O2
 
 dependencies:
@@ -54,7 +61,6 @@ dependencies:
   - hashable >=1.2.3.1
   - hspec >=2.1.2
   - hspec-smallcheck >=0.3.0
-  - integer-gmp >=0.5.1.0
   - lifted-base >=0.2.3.3
   - monad-control >=0.3.3.0
   - mono-traversable >=0.7.0
@@ -78,6 +84,13 @@ dependencies:
   - async >=2.0.2
   - contravariant >=1.3
   - bifunctors >=4.0
+when:
+  - condition: flag(integer-simple)
+    then:
+      dependencies: integer-simple >= 0.1.1.1
+    else:
+      dependencies: integer-gmp >= 0.5.1.0
+      cpp-options: -DINTEGER_GMP
 library:
   source-dirs: src
   other-modules:

src/Data/Store/Internal.hs

@@ -118,10 +118,15 @@ import           Foreign.C.Types ()
 import           Foreign.Ptr (plusPtr, minusPtr)
 import           Foreign.Storable (Storable, sizeOf)
 import           GHC.Generics (Generic)
+#ifdef INTEGER_GMP
 import qualified GHC.Integer.GMP.Internals as I
+import           GHC.Types (Int (I#))
+#else
+import           GHC.Types (Word (W#))
+import qualified GHC.Integer.Simple.Internals as I
+#endif
 import           GHC.Real (Ratio(..))
 import           GHC.TypeLits
-import           GHC.Types (Int (I#))
 import           Instances.TH.Lift ()
 import           Language.Haskell.TH
 import           Language.Haskell.TH.Instances ()
@@ -132,9 +137,11 @@ import           Prelude
 import           TH.Derive
 
 -- Conditional import to avoid warning
+#ifdef INTEGER_GMP
 #if MIN_VERSION_integer_gmp(1,0,0)
 import           GHC.Prim (sizeofByteArray#)
 #endif
+#endif
 
 ------------------------------------------------------------------------
 -- Utilities for defining list-like 'Store' instances in terms of 'IsSequence'
@@ -573,6 +580,7 @@ peekArray = do
 {-# INLINE peekArray #-}
 
 instance Store Integer where
+#ifdef INTEGER_GMP
 #if MIN_VERSION_integer_gmp(1,0,0)
     size = VarSize $ \ x ->
         sizeOf (undefined :: Word8) + case x of
@@ -640,6 +648,52 @@ instance Store Integer where
           when (r /= 0) (peekException "Buffer size stored for encoded Integer not divisible by Word size (to get limb count).")
           return (I.J# sz arr)
 #endif
+#else
+    -- May as well put in the extra effort to use the same encoding as
+    -- used for the newer integer-gmp.
+    size = VarSize $ \ x ->
+        sizeOf (undefined :: Word8) + case x of
+            I.Positive ds -> (1 + fromIntegral (numDigits ds)) * sizeOf (undefined :: Word)
+            I.Negative ds -> (1 + fromIntegral (numDigits ds)) * sizeOf (undefined :: Word)
+            I.Naught -> 0
+      where
+    poke x = case x of
+      I.Naught -> poke (0 :: Word8)
+      I.Positive ds -> do
+        poke (1 :: Word8)
+        poke (numDigits ds)
+        pokeDigits ds
+      I.Negative ds -> do
+        poke (2 :: Word8)
+        poke (numDigits ds)
+        pokeDigits ds
+      where
+        pokeDigits I.None = pure ()
+        pokeDigits (I.Some d ds) = poke (W# d) *> pokeDigits ds
+    peek = do
+      tag <- peek :: Peek Word8
+      case tag of
+        0 -> pure I.Naught
+        1 -> do
+          len <- peek :: Peek Word
+          I.Positive <$> peekDigits len
+        2 -> do
+          len <- peek :: Peek Word
+          I.Negative <$> peekDigits len
+        _ -> peekException "Invalid Integer tag"
+      where
+        peekDigits i
+          | i <= 0 = pure I.None
+          | otherwise = do
+              W# d <- peek
+              ds <- peekDigits (i - 1)
+              pure $! I.Some d ds
+
+numDigits :: I.Digits -> Word
+numDigits = go 0
+  where go !acc I.None = acc
+        go !acc (I.Some _ ds) = go (acc + 1) ds
+#endif
 
 -- instance Store GHC.Fingerprint.Types.Fingerprint where
 

test/Data/StoreSpec.hs

@@ -31,7 +31,9 @@ import           Data.IntSet (IntSet)
 import qualified Data.List.NonEmpty as NE
 import           Data.Map (Map)
 import           Data.Monoid
+#if !MIN_VERSION_primitive(0,7,0)
 import           Data.Primitive.Types (Addr)
+#endif
 import           Data.Proxy (Proxy(..))
 import           Data.Sequence (Seq)
 import           Data.Sequences (fromList)
@@ -285,8 +287,10 @@ spec = do
     describe "Store on all monomorphic instances"
         $(do insts <- getAllInstanceTypes1 ''Store
              omitTys0 <- sequence
-                 [ [t| Addr |]
-                 , [t| CUIntPtr |]
+#if !MIN_VERSION_primitive(0,7,0)
+                 [t| Addr |] :
+#endif
+                 [ [t| CUIntPtr |]
                  , [t| CIntPtr |]
                  , [t| IntPtr |]
                  , [t| WordPtr |]