WAI: Web Application Interface

     

This library provides a common interface for communication between web applications and web servers.
WAI cannot be used standalone, it requires a server handler such as warp.

Table of Contents

• Installation
• Application
• Middleware
• Contributing
• Changelog
• License

Installation

This library is not yet published to pursuit.
You can install this package by adding the details below to your packages.dhall:

Using Spago

let additions =
  { wai =
      { dependencies = [ "aff", "effect", "http-types", "node-net" ]
      , repo =
          "https://github.com/Woody88/purescript-wai.git"
      , version =
          "master"
      }
  , http-types =
      { dependencies = [ "tuples", "unicode", "generics-rep" ]
      , repo =
          "https://github.com/Woody88/purescript-http-types.git"
      , version =
          "master"
      }
  }

user@user:~$ spago install wai

Application

WAI models applications using a request-response flow.

type Application = Request -> (Response -> Aff ResponseReceived) -> Aff ResponseReceived

An application is a function that receives a request along with a continuation function for sending the response.

Middleware

Middleware is an application transformer. That is, a function from application to application:

type Middleware = Application -> Application

Because these are simply functions, they can be composed in any order.

middlewares :: Middleware 
middlewares = myCustomMiddleware1 >>> myCustomMiddleware2

myCustomMiddleware1 :: Middleware 
myCustomMiddleware1 app req send = ...

myCustomMiddleware2 :: Middleware 
myCustomMiddleware2 app req send = ...

This enables us to write declarative, composable middleware:

requireAuthToken :: Middleware 
requireAuthToken app req send 
    | hasAuthToken req = app req send 
    | otherwise        = send $ responseStr unauthorized401 [] "Missing Token!"
    where 
        hasAuthToken :: Request -> Boolean
        hasAuthToken req = ...

-- Creates a `Response` from a string. This helper function is provided by WAI. 
responseStr :: Status -> ResponseHeaders -> String -> Response

Contributing

If you are interested in fixing issues and contributing directly to the code base, please see the contributing guidelines.

Changelog

Change log details can be found here

License

Licensed under the MIT license. Copyright (c) 2021 Woodson Delhia. All rights reserved.