Source code in the elm programming language

import String exposing (reverse, length) 
import Html exposing (Html, Attribute, text, div, input)
import Html.Attributes exposing (placeholder, value, style)
import Html.Events exposing (on, targetValue)
import Html.App exposing (beginnerProgram)

-- The following function (copied from Haskell) satisfies the 
-- rosettacode task description.
is_palindrome x = x == reverse x

-- The remainder of the code demonstrates the use of the function 
-- in a complete Elm program.
main = beginnerProgram { model = "" , view = view , update = update }

update newStr oldStr = newStr

view : String -> Html String
view candidate =
  div []
    ([ input
        [ placeholder "Enter a string to check."
        , value candidate
        , on "input" targetValue 
        , myStyle
        ]
        []
     ] ++ 
     [ let testResult = 
             is_palindrome candidate

           statement = 
             if testResult then "PALINDROME!" else "not a palindrome"

       in div [ myStyle] [text statement]
     ])

myStyle : Attribute msg
myStyle =
  style
    [ ("width", "100%")
    , ("height", "20px")
    , ("padding", "5px 0 0 5px")
    , ("font-size", "1em")
    , ("text-align", "left")
    ]