Fable.Elmish.React Template

This template can be used to generate a simple web app with Fable and Elmish. You can find more templates by searching Fable.Template packages in Nuget.

Requirements

dotnet SDK 2.0.0 or higher
node.js 4.8.2 or higher
npm5: JS package manager

Although is not a Fable requirement, on macOS and Linux you'll need Mono for other F# tooling like Paket or editor support.

Editor

The project can be used by editors compatible with the new .fsproj format, like VS Code + Ionide, Emacs with fsharp-mode or Rider. Visual Studio for Mac is also compatible but in the current version the package auto-restore function conflicts with Paket so you need to disable it: Preferences > Nuget > General.

Installing the template

In a terminal, run dotnet new -i Fable.Template.Elmish.React::* to install or update the template to latest version.

In some shells you many need quotations: dotnet new -i "Fable.Template.Elmish.React::*". If you use dotnet SDK 2, you should only need to type dotnet new -i Fable.Template.Elmish.React.

Creating a new project with the template

In a terminal, run dotnet fable-elmish-react -lang F# to create a project in the current directory. Type dotnet new fable-elmish-react -n awesome instead to create a subfolder named awesome and put the new project there.

The project will have the name of the directory. You may get some issues if the directory name contains some special characters like hyphens

Building and running the app

Install JS dependencies: npm install
Move to src folder: cd src
Install F# dependencies: dotnet restore
Start Fable daemon and Webpack dev server: dotnet fable npm-start
In your browser, open: http://localhost:8080/

dotnet fable yarn-start (or npm-start) is used to start the Fable daemon and run a script in package.json concurrently. It's a shortcut of yarn-run [SCRIP_NAME], e.g. dotnet fable yarn-run start.

If you are using VS Code + Ionide, you can also use the key combination: Ctrl+Shift+B (Cmd+Shift+B on macOS) instead of typing the dotnet fable yarn-start command. This also has the advantage that Fable-specific errors will be highlighted in the editor along with other F# errors.

Any modification you do to the F# code will be reflected in the web page after saving. When you want to output the JS code to disk, run dotnet fable yarn-build (or npm-build) and you'll get a minified JS bundle in the public folder.

Project structure

Paket

Paket is the package manager used for F# dependencies. It doesn't need a global installation, the binary is included in the .paket folder. Other Paket related files are:

paket.dependencies: contains all the dependencies in the repository.
paket.references: there should be one such a file next to each .fsproj file.
paket.lock: automatically generated, but should committed to source control, see why.
Nuget.Config: prevents conflicts with Paket in machines with some Nuget configuration.

Paket dependencies will be installed in the packages directory. See Paket website for more info.

npm

package.json: contains the JS dependencies together with other info, like development scripts.
package-lock.json: is the lock file created by npm5.

JS dependencies will be installed in node_modules. See npm website for more info.

Webpack

Webpack is a bundler, which links different JS sources into a single file making deployment much easier. It also offers other features, like a static dev server that can automatically refresh the browser upon changes in your code or a minifier for production release. Fable interacts with Webpack through the fable-loader.

webpack.config.js: is the configuration file for Webpack. It allows you to set many things: like the path of the bundle, the port for the development server or Babel options. See Webpack website for more info.

F# source files

The template only contains two F# source files: the project (.fsproj) and a source file (.fs) in src folder.