On Mon, Oct 27, 2008 at 6:15 PM, Bart Massey
BTW, in case anyone is unclear, IEEE 854 supports a large variety of required and optional rounding modes; it takes no strong position on a "correct" rounding strategy. In particular, round-up ("round-half-up") and round-to-even ("round-half-even") are both required. However, there is an IEEE 854 subset, ANSI X3.274, that does make rounding modes other than round-up optional, presumably in conformance with common PL practice. This might make an implementation of the Report's round function on some FPU I've never heard of slightly more expensive.
I would like to see something on the lines of data RoundMode = RoundUp | RoundDown | RoundToZero | RoundHalfEven class (Real a, Fractional a) => RealFrac a where ... round :: (Integral b) => a -> b roundBy :: (Integral b) => RoundMode -> a -> b roundModes :: a -> [RoundMode] -- non-strict on argument ... -- Felipe.