maybe.elm

import Html exposing (text)

type alias User =
  { name : String
  , age : Maybe Int
  }

canBuyAlcohol : User -> Bool
canBuyAlcohol user =
  case user.age of
    Nothing ->
      False

    Just age ->
      age >= 21

user = User "Travis" (Just 37)

main =
  text <| toString <| canBuyAlcohol user