Hashp

Hashp is a better prn for debugging Clojure code. Inspired by projects like Spyscope, Hashp (ab)uses data readers to make it easier to get useful debugging data sent to STDOUT.

Usage

Once installed, you can add #p in front of any form you wish to print:

(ns example.core)

(defn mean [xs]
  (/ (double #p (reduce + xs)) #p (count xs)))

It's faster to type than (prn ...), returns the original result, and produces more useful output by printing the original form, function and line number:

user=> (mean [1 4 5 2])
#p[example.core/mean:4] (reduce + xs) => 12
#p[example.core/mean:4] (count xs) => 4
3.0

Installation

tools.deps

To use #p in a tools.deps project, add the following dependency to your project's deps.edn file:

{:deps {dev.weavejester/hashp {:mvn/version "0.3.0"}}}

You will then need to load the hashp.core namespace before using #p:

(require 'hashp.preload)

Leiningen

To make #p globally available to all Leiningen projects, add the following to ~/.lein/profiles.clj:

{:user
 {:dependencies [[dev.weavejester/hashp "0.3.0"]]
  :injections [(require 'hashp.preload)]}}

Boot

To make #p globally available to all Boot projects, add the following to ~/.boot/profile.boot:

(set-env! :dependencies #(conj % '[dev.weavejester/hashp "0.3.0"]))
(require 'hashp.preload)
(boot.core/load-data-readers!)

License

Copyright © 2025 James Reeves

Released under the MIT license.