Int64# was added in GHC 9.4.x

Author: TravisWhitaker

Data/Atomic.hs

@@ -43,14 +43,22 @@ import Data.IORef
 -- 64-bit machine, Int ~ Int64, do it the fast way:
 #if SIZEOF_HSINT == 8
 
+#if MIN_VERSION_base(4,17,0)
+int64ToInt :: Int64# -> Int#
+int64ToInt = int64ToInt#
+#else
+int64ToInt :: Int# -> Int#
+int64ToInt i = i
+#endif
+
 -- | A mutable, atomic integer.
 data Atomic = C (MutableByteArray# RealWorld)
 
 -- | Create a new, zero initialized, atomic.
 new :: Int64 -> IO Atomic
 new (I64# n64) = IO $ \s ->
     case newByteArray# SIZEOF_HSINT# s of { (# s1, mba #) ->
-    case atomicWriteIntArray# mba 0# (int64ToInt# n64) s1 of { s2 ->
+    case atomicWriteIntArray# mba 0# (int64ToInt n64) s1 of { s2 ->
     (# s2, C mba #) }}
 
 read :: Atomic -> IO Int64
@@ -61,19 +69,19 @@ read (C mba) = IO $ \s ->
 -- | Set the atomic to the given value.
 write :: Atomic -> Int64 -> IO ()
 write (C mba) (I64# n64) = IO $ \s ->
-    case atomicWriteIntArray# mba 0# (int64ToInt# n64) s of { s1 ->
+    case atomicWriteIntArray# mba 0# (int64ToInt n64) s of { s1 ->
     (# s1, () #) }
 
 -- | Increase the atomic by the given amount.
 add :: Atomic -> Int64 -> IO ()
 add (C mba) (I64# n64) = IO $ \s ->
-    case fetchAddIntArray# mba 0# (int64ToInt# n64) s of { (# s1, _ #) ->
+    case fetchAddIntArray# mba 0# (int64ToInt n64) s of { (# s1, _ #) ->
     (# s1, () #) }
 
 -- | Decrease the atomic by the given amount.
 subtract :: Atomic -> Int64 -> IO ()
 subtract (C mba) (I64# n64) = IO $ \s ->
-    case fetchSubIntArray# mba 0# (int64ToInt# n64) s of { (# s1, _ #) ->
+    case fetchSubIntArray# mba 0# (int64ToInt n64) s of { (# s1, _ #) ->
     (# s1, () #) }
 
 #else