[Haskell-beginners] Case Expressions

[Dean Herington]

And I'm not sure what going via integers (via `fromEnum`) buys you.  Why not:

interToBasic :: Interval -> BasicInterval
interToBasic a
     | a `elem` [MinorSecond, MajorSecond] = Second
     | a `elem` [MinorThird, MajorThird] = Third
...

Dean

At 6:27 PM -0400 5/28/09, Brent Yorgey wrote:
>On Thu, May 28, 2009 at 05:53:43PM -0400, Nathan Holden wrote:
>>
>  > interToBasic :: Interval -> BasicInterval
>  > interToBasic a = if (b == 1 || b == 2) then Second
>>                            else if (b == 3 || b == 4) then Third
>>  ..
>>  where b = fromEnum a
>>
>>  What I wanted to do, and figure is probably doable, but I can't seem to find
>>  it, is to say something like
>>
>>  case (fromEnum a) of
>>     1 || 2 -> Second
>>     3 || 4 -> Third
>>  ..
>>
>>  Is this doable? If so, what's the syntax?
>
>You can do this with pattern guards, like so:
>
>interToBasic a | b == 1 || b == 2  = Second
>	       | b == 3 || b == 4  = Third
>	       ...
>   where b = fromEnum a
>
>You could also use b `elem` [1,2] as an alternative to b == 1 || b ==
>2 (especially nice when there are more than two options).
>
>-Brent