Updating nested records, again

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Relevant issue on the compiler repo: https://github.com/elm/compiler/issues/984

I usually create helper funtions:

asBarIn : Foo -> Bar -> Foo
asBarIn foo bar =
    { foo | bar = bar }

Which can then be chained like this:

createBar 123
    |> asBarIn model.foo
    |> asFooIn model

In my experience this has been a nicer pattern than the flipped variant:

setBar : Bar -> Foo -> Foo
setBar bar foo =
    -- or `withBar`
    { foo | bar = bar }
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