defrag

A Clojure library designed to make wrapping defn forms possible for mortals.

Usage

You the user are responsible for writing a function that returns source code, which is called on a function's name args and body.

Print Example (pdefn)

Here's an example of such a function:

(defn wrap-print
  "Example of using a function to wrap various defn forms, which has
  access to argument forms."
  [name args body]
  `((println (pr-str {:name ~name :args ~args :body '~body})) ~@body))

Calling defrag! with a symbol and that function will tie them together

(defrag! pdefn wrap-print)

Now you can start defining functions with pdefn!

  (pdefn ^:private f
         ([] 1)
         ([x] (+ 2 x))
         ([x & ys] (first ys)))

Calling it produces:

  (f)
  ;; prints: {:args [], :name "f", :body [1]}
  ;;=> 1

  (f 2)
  ;; prints: {:args [2], :name "f", :body [(+ 2 x)]}
  ;;=>2

  (f 3 "hi" 5)
  ;; prints: {:args [3 ("hi" 5)], :name "f", :body [(first ys)]}
  ;;=> "hi"

  ;; notice our function is private and has the usual defn metadata:

  (:private (meta #'f))
  ;;=> true

  (:arglists (meta #'f))
  ;;=> ([] [x] [x & ys])

Prior Art

This library is based off of the work in https://github.com/viebel/defntly, which I would have used except there is no support for wrapping arguments.

I added some reader macros so that you can do e.g.:

#defrag/p
(defn ^:private f
  ([] 1)
  ([x] (+ 2 x))
  ([x & ys] (first ys)))

Instead of replacing the call of defn to pdefn directly.

License

Copyright © 2020 Bryan Maass

This program and the accompanying materials are made available under the terms of the Eclipse Public License 2.0 which is available at http://www.eclipse.org/legal/epl-2.0.

This Source Code may also be made available under the following Secondary Licenses when the conditions for such availability set forth in the Eclipse Public License, v. 2.0 are satisfied: GNU General Public License as published by the Free Software Foundation, either version 2 of the License, or (at your option) any later version, with the GNU Classpath Exception which is available at https://www.gnu.org/software/classpath/license.html.