bos:
Jason Dagit wrote:
I think, given my simple algorithm that means that (==) for ByteStrings is slower than (==) for String. Is this possible?
Yes indeed. Over ByteStrings, (==) is implemented as a call to memcmp. For small strings, this loses by a large margin because it has to go through the FFI.
Yes, a non-memcmp version can sometimes be profitably used here. Something like this Core: eq !n (Ptr p) (Ptr q) = inlinePerformIO $ IO $ go n p q where go !n p q s | n == 0 = (# s , True #) | otherwise = case readInt8OffAddr# p 0# s of (# s, a #) -> case readInt8OffAddr# q 0# s of (# s, b #) | a /=# b -> (# s, False #) | otherwise -> go (n-1) (plusAddr# p 1#) (plusAddr# q 1#) s Ok, so that's not Core, but it could be ;) -- Don