Learn Elm, Flow and Redwoodjs

`elm-ui` is a language for layout and interface design. This is a novel iteration on declarative styling where you can use Elm types and functions to define your UI in a declarative way.

The novel part is that it does not require you to know CSS to be used. The API is very simple and can be learned quickly!

The approach taken by `elm-ui` is based on two big ideas: 
Getting the compiler to verify as much of the layout and styling as possible by defining them in Elm code
Enabling refactoring capabilities of Elm for UI code


Elm is a programming language that provides a clean functional syntax for writing HTML web applications. It promises zero runtime exceptions, fast rendering, time-travel debugging, and much more.

Declarative UIs without CSS with elm-ui

Elm is a beginner friendly functional reactive programming language for building web applications. It contains a small but powerful set of language constructs, such as, static types, algebraic data types, immutability, and pure functions. Elm provides and requires the use of a specific architecture that’s well suited for sensible application construction. Elm’s type system and architecture may feel constraining at first, but they ultimately provide the programmer with some neat benefits including comprehensible code, and a much improved refactoring experience.

In this course you will learn the basic fundamentals of Elm so that you can start building applications today.

Start Using Elm to Build Web Applications

RedwoodJS takes the JAMstack philosophy to the next level. It brings together all the tools modern web development has to offer:

- React
- GraphQL
- Prisma

RedwoodJS abstracts database management away from you so that you can just build your schema and it will do all the plumbing. This collection will go over how to create a RedwoodJS project and the scripts that will help make your developer experience a joy.


Bringing full-stack to the JAMstack

Do you love the JAMstack philosophy but need a database-backed web app? Want great developer experience and easy scaling? Redwood is here! Built on React, GraphQL, and Prisma, Redwood works with the components and development workflow you love, but with simple conventions and helpers to make your experience even better.

redwoodjs

Introduction to RedwoodJS: full-stack framework for JAMstack

React is one of the web’s most popular frameworks for building JavaScript applications. 

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react

We use `yarn redwood generate page` (`yarn rw` for short) in this lesson to generate an `IndexPage` component. 

The first argument to `yarn rw generate page` is the name of the page you are generating. The second argument is the path you want the page to show up on. So `yarn rw generate page index /` will generate an `IndexPage` component and insert a route entry in our `web/src/Routes.js` file.

We learn that redwood import `React` for you so you don't have to import it manually when you are creating a component.

Generate a Page Using the Redwood CLI

In this lesson, we are going over how to generate a `RedwoodJS` project.

We can create a `RedwoodJS` project with `yarn create redwood-app ./my-redwood-project`.

`yarn` will generate the `RedwoodJS` app in the file folder you specified without installing any globals.

To run the `RedwoodJS` app, we use `yarn redwood dev`. This runs the Redwood client as well as the `GraphQL` backend.

Generate a Redwood Project

RedwoodJS provides a `Link` component that we can use to navigate around our app. We can provide a `to` prop with the path that we want to navigate to.

RedwoodJS takes this a step further and provides a `routes` object from `@redwoodjs/router`. This object is aware of all the routes defined in `web/Routes.js`. This allows us to use the methods on this object rather than referencing the our routes with a string literal. We can then change the route path without having to change all of the references to that route all over our app.

Use RedwoodJS Link and routes Object to Navigate

RedwoodJS gives us a cli command to generate layouts.

`yarn redwood generate layout main`

This will generate a `MainLayout` component in `src/layouts/MainLayout/`. We can use this layout component to define any headers or footers we want to share across multiple pages. 

Extract a RedwoodJS Layout Component

We are going to go ahead and install globally create-elm-app (because it has the best DX so far) and show how would you typically start any production-ready Elm app, and also add elm-ui as a dependency and show the first elements with elm-ui.

Bootstrap an elm-ui Application with create-elm-app

To showcase the power of elm-ui, in this lesson we will show how incredibly easy it is to center an element both horizontally and vertically on a screen with elm-ui, since this is a typical problem while doing regular CSS.

Center an elm-ui Element Horizontally and Vertically

In this lesson we will start to get to know the row and column functions in elm-ui to help us layout our application. We will choose the mobile first approach in which we will display everything in one column, show how to handle two columns and explain that later when we do responsible we will be able to play a bit more with this. Since the concept of margin does not exist in elm-ui, in this lesson we learn how to solve it by using spacing and we will talk about padding in a future lesson.

Model a Layout with row, column and spacing with elm-ui

We will use the pink box element that we had from previous lessons while implementing our fancy dashboard and we will turn it into our Card "component", the piece of UI that we are going to repeat and that will have its own state later on the course. 

To do this, we'll first manipulate the background color and text color, then change the height and width of the card. We will want to change the title for each of the cards and to do so we will accept a title argument that will be passed down to our text element within the card to be displayed.

Use View Functions to Create Reusable Pieces of UI in Elm

Since we mentioned in a previous lesson that there is no concept of "margin" in elm-ui, we are goint to learn how to se `padding`, `paddingXY` and `paddingEach` to compensate for that, and a little trick defining a value edges that is going to be pretty useful.

Use padding, paddingXY and paddingEach with elm-ui

We will style the heading of `viewCards` to look more like a real heading. If you inspect the console right now, you'll find that the `el` element we are using for our text corresponds to a div in HTML. 

We will go further away than using only text to display our content and introduce the modules `Element.Font` and `Element.Region` to fix the headlines and other text of our dashboard, adding an additional "breakdown" heading that is going to serve as a divider between sections.

Style Text with elm-ui Headlines, Typographies, and Fonts

In this lesson, we will explain when you would need to reach for the `text` function, why it is different from `textColumn` and `paragraph` and when to use each one as they serve different purposes for displaying text in the UI. Basically, `el` and `text` elements **do not wrap text by default**, so we need to use `paragraph` when we want text to overflow and still be visible to read. We will add a new "subtitle" section below our Breakdown subheading

Choose between text, textColumn and paragraph with elm-ui

Now that we have our cards more or less looking good lets add a button and style it as well so that it serves as a starting point for our dropdown component, this lesson will also help us to learn how to use the `Element.Input` module from elm-ui.

Work with elm-ui Input Components

Since there is no select or dropdown component backed in into elm-ui, we will be adding another dependency to our project called `PaackEng/elm-ui-dropdown` and adding to it additional styles and settings so that it looks and behaves exactly as we want to.

To make this works, we need to make a few changes:
- We need to add a `dropdownState : Dropdown.State String` to our `Model`
- Add a couple of extra variants to our `Msg` type: `OptionPicked (Maybe String)`, to be dispatched by our dropdown whenever we click on any option, and `DropdownMsg (Dropdown.Msg String)` to update the internal state of the dropdown from the outside.
- Construct our hardcoded list of options of type `List String`.
- Define a `dropdownConfig : Dropdown.Config String Msg` that is going to contain all our customisation of our dropdown.
- Use `Dropdown.view` to display our custom dropdown wherever we need it.

Customize My Own Dropdown with elm-ui-dropdown

Now that our dropdown is almost finished lets just drop some shadow in the options selector to make it more visually clear that its over any other element in our page. This is an attribute that we can control the `offset`, `size`, `blur`, and `color`.

We will want to do this to our `viewCard` as well. We will also make the `viewCard` function more flexible by adding additional `Html` attributes from the outside to make each card have a different **height.** That way any time you want to override default attributes, you can pass in a new style.

Add elm-ui Border.shadow to Highlight Any Element

This is the only lesson in which we will fallback to CSS to give our dropdown's scrollbar a fancier look because this is very browser dependent and there is no way (yet) to do this with elm-ui.

Customize My First Checkbox Icon with elm-ui

Up until this point, the 4 cards displayed in our dashboard each repeat the same information, so in this lesson, we will be splitting the state into different parts, showing an algebraic mindset and thinking how best represent the state of our app with our custom types. 

We'll start by modeling the selected options in state as a List of a Menu and String. The next step is to actually update the internal state of our menus. We will update `OptionPicked` to receive a string and when it does receive an option, it will filter for just the selected option and append that to state. Finally we will display the options in the `viewCard` component that will filter for the menu that is being selected and in the case of an option selected display that option as a string.

Split the Business Logic of Elm view Functions By Modeling the State

Since every time we interact with one of the dropdowns the information is shared between the 4 of them, the time as now arrives to give each individual dropdown its own state. We will also add subscriptions to listen to when the user clicks outside each dropdown!

To do this, we'll need to extend our state model to include each instance of our `viewCard`. To determine which dropdown that was clicked we will create a `getDropdownState` function that pattern matches the correct card instance. During this process, you'll see how the Elm compiler guides us through adding this functionality with detailed error messages.

You'll see how adding a subscription to close open dropdowns is convenient as `Dropdown` gives us an `onOutsideClick` function that receives the model and dropdown message.

Give Multiple Dropdowns Their Own Individual State with elm-ui-dropdown

We will make all the necessary changes to keep track within our model of the device and orientation that the user is using, and change our UI according with that information, adding responsiveness and multiple columns (at last!) to our dashboard.

To do this, we'll need to modify our app state to track the device height and width (which we expose from JavaScript). Then we can use the `classifyDevice` function to pattern match the devices we want to handle, in our case, `Desktop` and everything else (as mobile). We will add a `Browser.Events` subscription that sends a ResizedApp message to our model that defines what device we are on.

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