RandomDemoPair

elm-package.json

{
    "version": "1.0.0",
    "summary": "helpful summary of your project, less than 80 characters",
    "repository": "https://github.com/user/project.git",
    "license": "BSD3",
    "source-directories": [
        "."
    ],
    "exposed-modules": [],
    "dependencies": {
        "elm-lang/core": "3.0.0 <= v < 4.0.0",
        "evancz/elm-effects": "2.0.1 <= v < 3.0.0",
        "evancz/elm-html": "4.0.2 <= v < 5.0.0",
        "evancz/elm-http": "3.0.0 <= v < 4.0.0",
        "evancz/start-app": "2.0.2 <= v < 3.0.0"
    },
    "elm-version": "0.16.0 <= v < 0.17.0"
}

RandomDemo.elm

module RandomDemo where

import Html exposing (..) 
import Html.Events exposing (onClick)

import Random exposing (int, generate) 

import StartApp 
import Effects exposing (Effects)

type alias Model = { value : Int, seed : Random.Seed}

type Action = NewRandom 


init : Int -> Random.Seed -> Model 
init value initialSeed = Model value initialSeed

randInt : Random.Generator Int
randInt = int 10 100

update : Action -> Model -> Model 
update action model = 
  case action of 
    NewRandom -> (uncurry Model) <| generate randInt model.seed
      
view : Signal.Address Action -> Model -> Html
view address model =
  div []
  [ text <| toString model.value
  , br [] []
  , button [onClick address NewRandom][ text "Push for new random"]
  ]

noFx : (Action -> Model -> Model) -> Action -> Model -> (Model, Effects Action)
noFx update action model = (update action model, Effects.none)

app : StartApp.App Model
app = StartApp.start 
  { init = (init 42 (Random.initialSeed 42), Effects.none)
  , update = noFx update
  , view = view
  , inputs = []} 

main : Signal Html
main = app.html

RandomDemoPair.elm

import Html exposing (..) 
import Effects exposing (Effects, Never)
import Task exposing (Task)
import StartApp

import RandomDemo as RD
import Random exposing (generate, initialSeed, pair, minInt, maxInt, int)

type Action = Top RD.Action | Bottom RD.Action

type alias Model =
  { top : RD.Model
  , bottom : RD.Model
  }

init : (Model, Effects Action)
init = 
  let 
    ((int1, int2), _) = generate (pair (int minInt maxInt) (int minInt maxInt)) (initialSeed 42)
    (value, seed) = generate RD.randInt (initialSeed int1)
    (value', seed') = generate RD.randInt (initialSeed int2)
    top = RD.init value seed
    bottom = RD.init value' seed'
  in
    ( Model top bottom, Effects.none )

update : Action -> Model -> (Model, Effects Action)
update action model = 
  case action of 
    Top act -> 
      let 
        top' = RD.update act model.top 
      in 
        (Model top' model.bottom, Effects.none)

    Bottom act -> 
      let 
        bottom' = RD.update act model.bottom
      in 
        (Model model.top bottom', Effects.none)

view : Signal.Address Action -> Model -> Html
view address model =
  div []
  [ RD.view (Signal.forwardTo address Top) model.top
  , br [] [] 
  , RD.view (Signal.forwardTo address Bottom) model.bottom]


app : StartApp.App Model
app = StartApp.start
  { init = init
  , update = update
  , view = view
  , inputs = []}

main : Signal Html
main = app.html


port tasks : Signal (Task Never ()) 
port tasks = app.tasks