[Haskell-cafe] how can this code be less?

[Alexander Dunlap]

I think you're looking for Data.List.isInfixOf.

Alex

On Thu, Apr 24, 2008 at 7:40 PM, Dan Weston <westondan at imageworks.com> wrote:
> cetin tozkoparan wrote:
>
> > I wrote this code and Can it be less?
> > [2,4,5] list is sub list of [3,7,*2,4,5*,9] list and return True but not
> of [3,7,*4,2,5*,9] list ; return False
> >
> > sublist :: Eq a => [a] -> [a] -> Bool
> > sublist [] _     = True
> > sublist (_:_) []   = False
> > sublist (x:xs) (y:ys)
> >  | x == y      =  if isEqual (x:xs) (y:ys) == False
> >                        then sublist (x:xs) ys
> >                        else True
> >  | otherwise   = sublist (x:xs) ys
> >
> > isEqual :: Eq a => [a] -> [a] -> Bool
> > isEqual [] _     = True
> > isEqual (_:_) [] = False
> > isEqual (x:xs) (y:ys)
> >  | x==y    = isEqual xs ys
> >  | otherwise    = False
> >
>
>  One way is to use existing library functions as Henning suggested (but
> maybe you missed it because he mischievously changed the subject!)
>
>  Henning Thielemann wrote:
>  > try 'List.tails' and 'List.isPrefixOf'
>
>  You should be able to define sublist using only some combination of the
> following (and one pair of parentheses) in one line of code!
>
>  import List(isPrefixOf,tails)
>
>  (.)        :: (b -> c) -> (a -> b) -> a -> c
>  any        :: (a -> Bool) -> [a] -> Bool
>  tails      :: [a] -> [[a]]
>  isPrefixOf :: (Eq a) => [a] -> [a] -> Bool
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