Filter [Node] to [Element] with ghcjs-dom

Question

I am using ghcjs-dom. How can I filter the elements out of an array of nodes?

import GHCJS.DOM.Types

nodesToElements :: [Node] -> [Element]
nodesToElements = ??

or

nodesToElements :: [Node] -> IO [Element]
nodesToElements = ??

Answer 1

import GHCJS.DOM.Types
import Data.Maybe (mapMaybe)

nodeToElement :: Node -> Maybe Element
nodeToElement node = if node `isA` gTypeElement
                     then Just $ castToElement node
                     else Nothing

nodesToElements :: [Node] -> [Element]
nodesToElements = mapMaybe nodeToElement