jhc potentially has Word128, but it only has meaning when __int128_t is defined for a given target. (gcc + x86_64 for instance). What would something like Word256 mean? As in, the only reason to supply something like Word128 in the compiler is so FFI calls involving __int128_t will work, without a defined ABI type to map Word256 to, then a portable pure haskell implementation seems just as good. Your example doesn't seem to make sense, as the calling convention for __int128_t (what Word128 would map to) and double x[2] are unlikely to coincide. they are probably passed in different registers for instance. Adding the ability for the FFI to pass complex types directly would be useful. Something like 'CComplex CDouble' has been proposed before.. but that again would be independent of a Word128 type. John -- John Meacham - ⑆repetae.net⑆john⑈ - http://notanumber.net/