Get a element index in a List on Elm for list without duplicates

gistfile1.txt

getElementIndex : a -> List a -> Maybe Int
getElementIndex element list =
    let
        reducer item (index, found) =
          if found then
            (index, True)
          else
            if element == item then
                (index, True)
            else
                (index+1, False)
        
        folded =
          List.foldl reducer (0, False) list
    in
      if Tuple.second folded then
        Just <| Tuple.first folded 
      else
        Nothing