https://github.com/georgejahad/debug-repl.git
git clone 'https://github.com/georgejahad/debug-repl.git'
(ql:quickload :georgejahad.debug-repl)
The Clojure debug-repl
Every time I stick a println into some Clojure code to debug it, I think to myself, “This is Lisp! I should be able to insert a repl here!”
The problem is of course that Clojure's eval function doesn't know about the surrounding lexical scope. How to solve the problem? Create a macro that passes a copy of the lexical scope in with the form to be evaled, something like this:
(defn eval-with-locals [locals form] (eval `(let ~(generate-local-bindings locals) ~form)))
USE: The interface is meant to be dead simple: “(use 'alex-and-georges.debug-repl)” loads it, and “(debug-repl)” invokes it.
That's about it. When you enter the debug-repl, the regular repl prompt will be replaced with
dr ⇒
An example will make it clearer:
user⇒ (let [c 1 d 2] (defn a b c d))
user⇒ (a “foo” “bar”)
dr-1-1001 ⇒ c “bar”
dr-1-1001 ⇒ d 2
dr-1-1001 ⇒ locals {fn__104 #<user$eval__103 user$eval__103@5f6303>, c “bar”, d 2, fn__106 #<user$eval__103$a__105 user$eval__103$a__105@179dce4>, b “foo”, counter__56__auto__ 1001}
dr-1-1001 ⇒ (str b c) “foobar”
dr-1-1001 ⇒ () 2 user⇒
LIMITATIONS: The debug-repl doesn't currently integrate properly with the slime-repl, (I think because of how Slime manages IO redirection,) so you'll have to invoke it from a regular repl, or slime's inferior lisp buffer.
A version of the debug-repl has been ported to slime. More details here: http://hugoduncan.org/post/2010/swank_clojure_gets_a_break_with_the_local_environment.xhtml