Reading the site&#x27;s description of the video, it&#x27;s more like &quot;how languages like Haskell and Elm are informing the design of Javascript libraries like Redux&quot;. So it&#x27;s not so much Elm and Haskell TEACHING &quot;mainstream&quot; JS (whatever that is) but one library merely taking hints from other programming domains that are relevant to the particular use case it&#x27;s trying to cover.