[Haskell-beginners] Using findIndex and then splitAt in Data.List

[David McBride]

You will probably do a case match on the result of findIndex to find out
whether you want to split there.  You will have to deal with the
possibility that the item you are searching for is not in the list.
Untested:

let twoListsTuple = case findIndex (\g -> (itemName g) == (itemName
gradeItemP)) gradeItemList of
  Nothing -> (gradeItemList,[])
  Just newlists -> newlists

On Fri, Feb 27, 2015 at 3:51 PM, Geoffrey Bays <charioteer7 at gmail.com>
wrote:

> Hi.
> An elementary question here about two functions in Data.List:
>  how to use a value from findIndex which returns a Maybe Int,
> and then use that result in splitAt which takes a regular Int?
> This is in an IO() do
>
> Like so: (This is in an IO() do block)
>
>     let gradeItemIndex = findIndex (\g -> (itemName g) == (itemName
> gradeItemP)) gradeItemList
>     let twoListsTuple = splitAt  gradeItemIndex gradeItemList
>
> // does not compile obviously
>
> Many Thanks,
>
> Geoffrey
>
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