Wisp is a practical Gleam web framework for rapid development and easy maintenance. We worry about the hassle of web development, and you focus on writing your application.

It is based around two concepts: handlers and middleware.

Handlers

A handler is a function that takes a HTTP request and returns a HTTP response. A handler may also take other arguments, such as a "context" type defined in your application which may hold other state such as a database connection or user session.

import wisp.{type Request, type Response}

pub type Context {
  Context(secret: String)
}

pub fn handle_request(request: Request, context: Context) -> Response {
  wisp.ok()
}

Middleware

A middleware is a function that takes a response returning function as its last argument, and itself returns a response. As with handlers both middleware and the functions they take as an argument may take other arguments.

Middleware can be applied in a handler with Gleam's use syntax. Here the log_request middleware is used to log a message for each HTTP request handled, and the serve_static middleware is used to serve static files such as images and CSS.

import wisp.{type Request, type Response}

pub fn handle_request(request: Request) -> Response {
  use <- wisp.log_request
  use <- wisp.serve_static(request, under: "/static", from: "/public")
  wisp.ok()
}

Learning Wisp

The Wisp examples are a good place to start. They cover various scenarios and include comments and tests.

• Hello, World!
• Routing
• Working with form data
• Working with JSON
• Working with other formats
• Using a database
• Serving static assets
• Logging
• Working with cookies
• Configuring default responses
• Working with files

API documentation is available on HexDocs.

Wisp applications

These open source Wisp applications may be useful examples.

• https://packages.gleam.run/: A HTML serving application that uses an SQLite + LiteFS database, deployed to Fly.io.