Functional. Reactive. Beautiful. Try pasting this at http://elm-lang.org/try

frp.elm

import Html exposing (iframe, Html)
import Html.Attributes exposing (seamless, attribute, height)
import String exposing (concat, join)

-- FIXME
secure_required : Bool
secure_required = True

protocol : String
protocol =
  if secure_required
    then "https"
    else "http"

join_path : List String -> String
join_path fragments =
  join "/" fragments

query_item : String -> String -> String
query_item k v =
  k ++ "=" ++ v

join_query : List String -> String
join_query kvs =
  join "&" kvs

full_url : String -> List String -> List String -> String
full_url domain paths queries =
  concat [ protocol
         , "://"
         , domain
         , "/"
         , join_path paths
         , "?"
         , join_query queries
         ]

target_url : String -> String
target_url id =
  full_url "youtube.com" ["embed", id] ["autoplay=1", "showinfo=0", "controls=0"]
  
src : String -> Html.Attribute
src value = attribute "src" value
  
frameborder : String -> Html.Attribute
frameborder value = attribute "frameborder" value

width : String -> Html.Attribute
width value = attribute "width" value

embed : String -> Html
embed url =
  iframe [ seamless True, src url, frameborder "0", width "100%", height 800] []

main = embed (target_url ("UJDhBU-LneM"))