July 2019
Intermediate to advanced
310 pages
7h 26m
English
Content preview from Programming Elm
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Simplify Messages
The update function suffers from code duplication and unnecessary complexity. In this section, you will simplify it by reducing the messages it handles. You will learn how to collapse multiple message values into one parameterized message value.
Look for the update function near the bottom of SaladBuilder.elm. This function is over 100 lines, so we have a problem.
| | update : Msg -> Model -> ( Model, Cmd Msg ) |
| | update msg model = |
| | case msg of |
| | SelectLettuce -> |
| | ( { model | base = Lettuce } |
| | , Cmd.none |
| | ) |
| | -- other branches |
Notice the duplication where we handle the ToggleTomatoes, ToggleCucumbers, and ToggleOnions messages. Surprisingly, we have duplication with the other salad-related messages for ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.