How to update nested fields in record

Main.elm

module Main exposing (..)


type alias Bar =
    { baz : String }


type alias Foo =
    { bar : Bar }


type alias Model =
    { foo : Foo }


model : Model
model =
    { foo = { bar = { baz = "hello world" } } }


setFoo : (Foo -> Foo) -> Model -> Model
setFoo fn model =
    { model | foo = fn model.foo }


setBar : (Bar -> Bar) -> Foo -> Foo
setBar fn foo =
    { foo | bar = fn foo.bar }


setBaz : String -> Bar -> Bar
setBaz str bar =
    { bar | baz = str }


updateBaz : String -> Model -> Model
updateBaz str =
    (setFoo <| setBar <| setBaz str)


update : Model
update =
    model |> updateBaz "foo bar baz"