In Haskell, what's the canonical way of declaring a top-level array (Data.Vector of a huge list of doubles, in my case)? Performance is key in my case. The straightforward way would just be something like: globalArray :: V.Vector Double globalArray = V.fromList [ huge list of doubles ] {-# NOINLINE globalArray #-} However, I don't want to have to run the fromList at runtime. Not only would this mean a bigger executable (having to store a linked list, instead of an array), it would be quite inefficient since we don't even use the source list! Therefore, I was thinking of storing the array in a C file: static const double globalArray[] = { huge list of doubles }; double* getGlobalArray() { return globalArray; } int getGlobalArraySize() { return sizeof(globalArray)/sizeof(globalArray[0]); } And importing it in haskell witht he FFI, followed with an unsafeCast: foreign import ccall unsafe "getGlobalArray" c_globalArray :: Ptr CDouble foreign import ccall unsafe "getGlobalArraySize" c_globalArraySize :: CInt globalArray :: V.Vector Double globalArray = V.unsafeCast $ unsafeFromForeignPtr0 (unsafePerformIO $ newForeignPtr_ c_globalArray) (fromIntegral c_globalArraySize) {-# NOINLINE globalArray #-} But this version (clearly) is full of "unsafe"ty. Is there a better way that I haven't thought of? Regards, - clark