How to validate form fields which should have same values about elm-form HOT 5 CLOSED

validate : Validation CustomError User
validate =
    map8
        User
        (field "name" (string |> andThen nonEmpty))
        (field "email" (email |> andThen (asyncCheck True)))
        (field "password" (string |> andThen (minLength 4)))
        ((field "password" string) |> andThen validateConfirmation)
        (field "admin" (bool |> defaultValue False))
        (field "date" date)
        (field "profile" validateProfile)
        (field "todos" (list validateTodo))


validateConfirmation : String -> Validation CustomError String
validateConfirmation password =
    field "passwordConfirmation"
        (string
            |> andThen
                (\confirmation ->
                    if password == confirmation then
                        succeed confirmation
                    else
                        fail (customError ConfirmationError)
                )
        )

validate : Validation String User
validate =
    succeed User
        |> andMap (field "name" (string |> withCustomError "Input Name !"))
        |> andMap (field "password" (string |> withCustomError "Input Password !"))
        |> andMap ((field "password" string) |> andThen validateConfirmation)


validateConfirmation : String -> Validation String String
validateConfirmation password =
    field "passwordConfirmation"
        (string
            |> andThen
                (\confirmation ->
                    if password == confirmation then
                        succeed confirmation
                    else
                        fail (customError "Confirmation Error")
                )
        )

validate : Validation String User
validate =
    succeed User
        |> andMap (field "name" (string |> withCustomError "Input Name !"))
        |> andMap (field "password" (string |> withCustomError "Input Password !"))
        |> andMap 
            (oneOf 
                [ (field "password" string) |> andThen validateConfirmation
                , emptyString |> andThen validateConfirmation
                ]
              )


validateConfirmation : String -> Validation String String
validateConfirmation password =
    field "passwordConfirmation"
        (string
            |> withCustomError "Input Password Confimation !"
            |> andThen
                (\confirmation ->
                    if password == confirmation then
                        succeed confirmation
                    else
                        fail (customError "Confirmation Error")
                )
        )