[Haskell-beginners] Use a list as data for a data type?

[Brent Yorgey]

On Fri, Feb 22, 2013 at 02:07:43PM -0500, Brent Yorgey wrote:
> On Fri, Feb 22, 2013 at 10:43:32AM -0800, Bryce Verdier wrote:
> > Lets say I have a data type like so:
> > 
> > data IpAddress = IpAddress {$
> >          o1 :: !Int,$
> >          o2 :: !Int,$
> >          o3 :: !Int,$
> >          o4 :: !Int$
> >      } deriving (Show)$
> > 
> > which you can create by doing:
> > IpAddress 192 168 1 1
> > 
> > Is there a way to do the same thing with the input data in a list? Like:
> > IpAddress [192,168,1,1]
> > 
> > or using some operator (or combination of operators):Like (I'm
> > guessing (<????>) isn't in use):
> > IpAddress <????> [192,168,1,1]
> 
> No, there isn't.  But you can make a function
> 
>   ipAddress :: [Int] -> IpAddress
>   ipAddress [a,b,c,d] = IpAddress a b c d

For that matter you can define the operator (<????>) yourself:

(<????>) :: (a -> a -> a -> a -> b) -> [a] -> b
f <????> [a,b,c,d] = f a b c d

Not sure how useful it is though.

-Brent