On Monday 01 November 2010 16:59:33, Angel Alonso wrote:

Hi,

I have the following piece of code:

n = 3 case n of 3 -> "Something" 4 -> "Something" _ -> "Other"

Is it possible to shorten the case statement into something like this?:

n = 3 case n of 3 or 4 -> "Something" _ -> "Other"

No, case does a pattern match. You can do case n of _ | n `elem` [3,4] -> "Something" | otherwise -> "Other" however, which becomes really useful if you have case expression of pat1 | cond11 -> thing11 | cond12 -> thing12 | otherwise -> thing1Other pat2 | cond21 -> thing21 ...

Thanks.

-- Angel Alonso

Hi,

I have the following piece of code:

n = 3 case n of 3 -> "Something" 4 -> "Something" _ -> "Other"

Is it possible to shorten the case statement into something like this?:

n = 3 case n of 3 or 4 -> "Something" _ -> "Other"

Is the following what you are looking for? case n of _ | n == 3 || n == 4 -> "something" _ -> "other" Some reminders: * Guards are allowed in case expressions * _ is not a special keyword in haskell. It's a regular variable so will always match. It's usually used when you don't use it's value in the right hand side or when it adds no information. In this case its value will be n so there is no reason to introduce another name. Also if you just have one special case you could use if then else: if n == 3 || n ==4 then "something" else "other" Another solution is to take the common expression out. This is useful if you are matching more complex structures in your case expression: let st = "something" in case n of Left x | x == 3 || x == 4 -> st Right _ -> st _ -> "other" Best regards.