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Wai-routes is a micro web framework for Haskell that focuses on typesafe URLs.

Wai-routes is based on the Haskell Web Application Interface and uses it for most of the heavy lifting. It also provides a convenient but thin veneer over most of the wai API so it is unnecessary to directly use raw wai APIs when building web apps.

Much of Wai-route’s typesafe URL functionality was pulled from the corresponding features in Yesod, and indeed the underlying aim of wai-routes is - “To provide a similar level of typesafe URL functionality to Wai applications as is available to Yesod applications.”.

Note - If you are looking for typesafe URLs for Snap, take a look at Snap-Routes - A port of this library for Snap.


Wai-routes adds the following features on top of wai -


When it comes to performance, Wai-routes compares quite favorably with other Haskell web development micro frameworks.

See more details here - philopon/apiary-benchmark


Example Usage

Wai-routes comes with several examples in the examples/ directory. New examples are being added regularly.

Example 1. Hello World - Code

A simple hello-world web app with two interlinked pages. This provides the simplest example of using routing and linking between pages with typesafe routes.

Example 2. Hello World with Subsites - Code

Similar functionality as the first example, but uses a hello world subsites to provide the hello world functionality. A subsite is an independently developed site that can be embedded into a parent site as long as the parent site satisfies a particular api contract. It’s easy to swap out subsites for different functionality as long as the api contract remains constant.

Example 3. Using Blaze-HTML to generate HTML - Code

A simple example of how to generate HTML using blaze-html combinators in your handlers.

Example 4. Using Shakespearean Templates (hamlet, cassius, lucius, julius) to generate HTML/CSS/JS - Code

A simple example of how to generate HTML/CSS/JS using shakespearean templates. You can use both external and inline templates.

Example 5. Using Digestive Functors and Hamlet - Code

An example of using digestive functors for form handling and hamlet for templating. It demonstrates composing nested forms with validation, nested views defined in hamlet templates, and how to wire it together with wai-routes.

Example 6. Building a JSON REST Service - Code

Provides a simple example of how to build JSON REST services with wai-routes. Uses Aeson for JSON conversion. Note that this example just demonstrates the web facing side of the application. It doesn’t permanently persist data, and is also not threadsafe. You must use a more robust data storage mechanism in production! An example of doing this with a Relational DB adapter (like persistent) is in the works.

Example 7. Stream a response - Code

Wai has had the ability to stream content for a long time. Now wai-routes exposes this functionality with the stream function. This example shows how to stream content in a handler. Note that most browsers using default settings will not show content as it is being streamed. You can use “curl” to observe the effect of streaming. E.g. - curl localhost:8080 will dump the data as it is being streamed from the server.

Example 8. Kitchen sink - Code

Work in progress. Demonstrates all major features in wai-routes.

Example 9. Unrouted - Code

Demonstrates “unrouted” applications. These require no TH, or GHC extensions. Basically allow you to sequence request handlers in a cascade, with each handler having the full functionality of HandlerM monad available to them. Each handler also has access to untyped (but parsed) route information. Unrouted handlers are freely mixable with typesafe routing.

Example 10. Typesafe “Bare” Wai routing - Code

Demonstrates writing no-overhead “bare” wai applications with routing. Wai-routes handlers are simple functions that return wai responses. This means that you are free to use typesafe routing, but without using runHandlerM, instead accessing the master datatype and the route args as arguments passed to the handler function.


The current recommended route (pun not intended) for deploying wai-routes apps is keter. You need to read the port from the environment variables -

-- Run the application
main :: IO ()
main = do
  port' <- getEnv "PORT"
  let port = read port'
  run port $ waiApp application

Then put something like this in config/keter.yaml -

exec: ../path/to/executable

Then create a tarball with config/keter.yaml, path/to/executable, and any other files needed at runtime for your application. Rename the tarball to have a .keter extension.

Upload that file to your server’s incoming folder for keter to pick it up. You obviously need keter already installed and configured properly at the server.

Planned Features

The following features are planned for later releases -