Henning Thielemann
On Thu, 26 Mar 2009, Xiao-Yong Jin wrote:
So I have another question. Is the following function safe and legitimate?
safeDiv :: (Exception e, Integral a) => a -> a -> Either e a safeDiv x y = unsafePerformIO . try . evaluate $ div x y
I believe it should be okay to use this 'safeDiv'. What do
I think that question is wrong way around. The real question is, why do you want to solve your problem using unsafePerformIO?
I just want to know, from a theoretical point of view, whether this 'safeDiv' in above definition is the same as
safeDiv' :: (Exception e, Integral a) => a -> a -> Either e a safeDiv' _ 0 = Left e safeDiv' x y = Right $ div x y
For the question why do I want to do that, I am not sure. I guess if the function which has an error call inside is provided by other library package, and I don't have a clear and easy way to tell whether the function will make the error call or not, it would be easy just to make a wrapper like that. It's also a possible situation that I don't know how to test the input to a foreign function call. -- c/* __o/* <\ * (__ */\ <