[Haskell-cafe] Re: Looking for largest power of 2 <= Integer

Dan Piponi wrote:

There's a bit of work required to make this code good enough for general consumption, and I don't know much about Haskell internals.

(1) What is the "official" way to find the size of a word? A quick look at 6.8.1's base/GHC/Num.lhs reveals that it uses a #defined symbol.

I'm not 100% sure what you mean by "word" in this context, but assuming you mean the same thing as we do in GHC when we say "word" (a pointer-sized integral type), then one way is Foreign.sizeOf (undefined :: Int) or Foreign.sizeOf (undefined :: Ptr ()) (in GHC these are guaranteed to be the same). There's also Data.Bits.bitSize (undefined :: Int) which might be more appropriate since you're using Data.Bits anyway. Cheers, Simon