Compojure is a concise routing library for Ring, a Clojure web application library. It provides a simple and expressive way to define routes and handle HTTP requests in Clojure web applications, making it easier to create RESTful APIs and web services.

Pros

• Simple and intuitive syntax for defining routes
• Seamless integration with Ring and other Clojure web libraries
• Supports route nesting and parameter extraction
• Lightweight and minimal, allowing for easy customization

Cons

• Limited built-in features compared to full-stack web frameworks
• May require additional libraries for more complex web applications
• Learning curve for developers new to Clojure or functional programming
• Less active development in recent years

Code Examples

1. Basic route definition:

(ns myapp.handler
  (:require [compojure.core :refer :all]
            [compojure.route :as route]))

(defroutes app-routes
  (GET "/" [] "Hello World")
  (GET "/users/:id" [id] (str "User " id))
  (POST "/api/data" request (handle-data request))
  (route/not-found "Not Found"))

2. Route nesting and middleware:

(defroutes api-routes
  (GET "/items" [] (get-items))
  (POST "/items" [] (create-item)))

(def app
  (-> (routes
        (context "/api" [] api-routes)
        (route/not-found "Not Found"))
      (wrap-json-response)
      (wrap-json-body)))

3. Using destructuring in route handlers:

(defroutes app-routes
  (GET "/search" [q :<< params]
    (str "Searching for: " q))
  (GET "/user/:id" {{id :id} :params}
    (str "User ID: " id)))

Getting Started

To use Compojure in your Clojure project, add the following dependency to your project.clj file:

[compojure "1.7.0"]

Then, in your namespace, require Compojure:

(ns myapp.core
  (:require [compojure.core :refer :all]
            [compojure.route :as route]))

(defroutes app-routes
  (GET "/" [] "Hello, Compojure!")
  (route/not-found "Not Found"))

(def app app-routes)

This sets up a basic Compojure application with a single route. You can now run this application using a Ring-compatible web server like Jetty or HTTP Kit.