Minimal example

Topbar.elm

module Topbar exposing (..)

import Http
import Task exposing (..)

type Msg =
  NoOp
  | Error Http.Error
  | Success String

makeHttpCall : String -> Task Http.Error String
makeHttpCall url =
  Http.getString url
  
performHttp : Cmd Msg
performHttp = 
  Task.perform Error Success makeHttpCall
  
update : Msg -> Model ->  (Model, Cmd)
update msg model =
  case msg of
    NoOp -> model ! []
    
    Error _ -> model ! []
    
    Success content -> { model | content = content } ! []