remove IsMultipleOf type foo to build on older ghc

1 files changed, 5 insertions, 0 deletions

diff --git a/haskell/Data/Primitive/ByteArray/Util.hs b/haskell/Data/Primitive/ByteArray/Util.hs
index de944e7..83a2e7d 100644
--- a/haskell/Data/Primitive/ByteArray/Util.hs
+++ b/haskell/Data/Primitive/ByteArray/Util.hs
@@ -7,6 +7,7 @@
 {-# LANGUAGE ScopedTypeVariables   #-}
 {-# LANGUAGE TypeFamilies          #-}
 {-# LANGUAGE TypeOperators         #-}
+{-# LANGUAGE CPP                   #-}
 module Data.Primitive.ByteArray.Util where
 
 import GHC.Exts (Ptr(..))
@@ -37,7 +38,9 @@ instance n ~ (q * k) => IsMultipleOf n k
 
 writeAtByte :: ( Prim a
                , PrimMonad m
+#if __GLASGOW_HASKELL__ >= 802
                , IsMultipleOf n (SizeOf a)
+#endif
                ) => MutableByteArray (PrimState m) -> Offset n -> a -> m ()
 writeAtByte buf (Offset offset) a = writeByteArray buf (div offset $ (sizeOf a)) a
 {-# INLINE writeAtByte #-}
@@ -45,7 +48,9 @@ writeAtByte buf (Offset offset) a = writeByteArray buf (div offset $ (sizeOf a))
 readAtByte :: forall a m n.
                ( Prim a
                , PrimMonad m
+#if __GLASGOW_HASKELL__ >= 802
                , IsMultipleOf n (SizeOf a)
+#endif
                ) => MutableByteArray (PrimState m) -> Offset n -> m a
 readAtByte buf (Offset offset) = readByteArray buf (div offset $ (sizeOf (undefined :: a)))
 {-# INLINE readAtByte #-}