On 2015-05-05 00:54, Levent Erkok wrote:
I can see at least two designs:
* One where the rounding mode goes with the operation: `fpAdd RoundNearestTiesToEven 2.5 6.4`. This is the "cleanest" and the functional solution, but could get quite verbose; and might be costly if the implementation changes the rounding-mode at every issue.
* The other is where the operations simply assume the RoundNearestTiesToEven, but we have lifted IO versions that can be modified with a "with" like construct: `withRoundingMode RoundTowardsPositive $ fpAddRM 2.5 6.4`. Note that `fpAddRM` (*not* `fpAdd` as before) will have to return some sort of a monadic value (probably in the IO monad) since it'll need to access the rounding mode currently active.
Neither choice jumps out at me as the best one; and a hybrid might also be possible. I'd love to hear any insight you gain regarding rounding-modes during your experiment.
The monadic alternative is more readily extensible to handle IEEE 754's sticky flags: inexact, overflow, underflow, divide-by-zero, and invalid.