Random.elm

module Main exposing (..)

import Html exposing (div, button, ul, Html, li, text)
import Html.Attributes exposing (value, style)
import Html.Events exposing (onClick)
import Html.App as App
import Dict exposing (Dict)
import Random exposing (Seed)


type alias Child =
    { id : Int }


type alias Model =
    { children : Dict Int Child
    , seed : Seed
    }


type Msg
    = CreateChild


init : Model
init =
    { children = Dict.empty
    , seed = Random.initialSeed 42
    }


idGenerator : Random.Generator Int
idGenerator =
    Random.int 0 Random.maxInt


update : Msg -> Model -> Model
update msg model =
    case msg of
        CreateChild ->
            let
                ( rndInt, newSeed ) =
                    Random.step idGenerator model.seed

                newChild =
                    Child rndInt
            in
                { model | seed = newSeed, children = Dict.insert rndInt newChild model.children }


view : Model -> Html Msg
view model =
    div [ style [ (,) "margin" "50px" ] ]
        [ button [ onClick CreateChild ] [ text "Create Child" ]
        , ul [] (List.map viewChild <| Dict.values model.children)
        ]


viewChild : Child -> Html Msg
viewChild child =
    li [] [ text <| "Child with Id " ++ (toString child.id) ]


main : Program Never
main =
    App.beginnerProgram
        { model = init
        , update = update
        , view = view
        }