Hi,
On 10/25/06, Bulat Ziganshin
Hello Iavor,
Thursday, October 26, 2006, 4:51:00 AM, you wrote:
kb,mg,gb :: Num a => a kb = 1024 mb = 1024 * kb gb = 1024 * mb
b :kb :mb :gb :_ = iterate (1024*) 1 :: [Int] b_:kb_:mb_:gb_:tb_:_ = iterate (1024*) 1 :: [Integer]
and now we can write (4 * kb) instead for 4096.
btw, your variant requires re-calculating values on each their use
There are other integral types for which one might use these constants (e.g., Word16 and Word32), so the overloading is useful. The multiplications might be repeated depending on the compipler but, as other people pointed out, this is a fairly easy optimization to perform and GHC probably does it. The overloading might make things a little more tricky, but it should be still doable (it is the same problem as turning 1+2 into 3 at compiple time). On the other hand, none of these are important, if we were to use the literal notation that I suggested. Then, the multiplications would happen in the lexer when we compute the value for the literal. I think that the main advantage of the literals is that they are more readable. For example, an editor can color them in the same way as it colors other literals. -Iavor