main3.elm

module Main exposing (..)

import Html exposing (..)
import Html.Attributes exposing (..)
import Html.Events exposing (..)


main =
    Html.beginnerProgram { model = model, view = view, update = update }


type alias UserInfo =
    { name : String, age : Int }


type alias Coach =
    { name : String, age : Int, sports : String }


model =
    UserInfo "" 0


getUserAge : UserInfo -> Int
getUserAge record =
    record.age


printAge =
    let
        sam =
            UserInfo "Sam" 24

        charlie =
            Coach "Charlie" 52 "Basketball"
    in
    sam.name ++ " is " ++ toString sam.age ++ " " ++ charlie.name ++ " is " ++ toString charlie.age


type Msg
    = Noop


update : Msg -> UserInfo -> UserInfo
update msg model =
    model


view : UserInfo -> Html Msg
view model =
    div [] [ text printAge ]

This example is incorrect. You don't even use the getUserAge function. And you're wrong, getUserAge does not work with Coach type, it only works with "sam" , since sam is UserInfo type

^ I agreed. Like I tried writing down the similar code on Elm examples playground, that code puts an error.
Here's my code I wrote with your example: https://gist.github.com/SoshiHomma/2b75dced243a95e8831ee4e01a29cc0c