Comments on: Initial Thoughts on Clojure

By: ndanger.organism :: blog :: Polyglotism: not over your head, just overhead

ndanger.organism :: blog :: Polyglotism: not over your head, just overhead — Fri, 07 Aug 2009 20:06:10 +0000

[...] Finally there’s the cost of tools & debugging. You now need tooling–compilers, debuggers, syntax-aware editors–for several languages. More languages can lead to more complexity. Making matters worse, error messages across language boundaries are often cryptic, even when both languages are on the JVM. [...]

By: Glen Stampoultzis

Glen Stampoultzis — Tue, 21 Jul 2009 06:14:06 +0000

Regarding stack traces it’s probably also worth looking at this:

http://github.com/mmcgrana/clj-stacktrace/tree/master

By: Basu

Basu — Tue, 21 Jul 2009 02:40:38 +0000

It’s interesting to know your experiences in Clojure. I’ve had some experience with Scheme (first half of SICP mostly) and now i’m looking into Common Lisp do some real-world stuff. I’m thinking of looking into writing some server software working with client JavaScript. I haven’t looked at Clojure yet, but for now my favorite VM language is Scala (as long as static typing doesnt get in my way)

By: Phil

Phil — Mon, 20 Jul 2009 22:56:32 +0000

deong: Pressing “1″ is no longer necessary in recent versions of swank-clojure.

In addition, I’ve just pushed out a fix that dims irrelevant lines from stack traces. This makes the important lines jump out at you much more quickly. Try it out if you’re already using swank-clojure.

By: admin

admin — Mon, 20 Jul 2009 19:14:16 +0000

Thanks for the catches! I’m updating the post to have the correct syntax in the cases I made mistakes.

By: Brian

Brian — Mon, 20 Jul 2009 19:13:11 +0000

Note that `for` isn’t a loop, it’s a list comprehension. `doseq` is a loop. Probably doesn’t have anything to do with your error messages but a lot of people use `for` when they want `doseq`.

I think that the (.method obj) form is used more often by most people than (. obj method), because (function obj) is more Lispy.

By: mb

mb — Mon, 20 Jul 2009 18:58:50 +0000

This syntax is wrong:

(cond ((> num 0) 1
( num 0) 1
( instead of .. since it also allows functions/macros, not only methods.

(-> someObject .callMethod (call-normal-clojure function with more args) (.another method) …)

Notable is also doto:

(doto some-object
.callSomethingOnObject
(.callOtherMethodOnObject with args)
(works-also-with-functions on the object))

Another note: This does not make sense to me:

(defn make-rectangle
([width] {:width width :height width})
([width height] (make-rectangle width height)))

It should probably read:

(defn make-rectangle
([width] (make-rectangle width width))
([width height] {:width width :height height}))

By: Luís

Luís — Mon, 20 Jul 2009 17:09:47 +0000

Your COND example has an extra pair of parenthesis. It should read:

(cond
((> num 0) 1)
(( num 0) (do-this) 1)
((< num 0) (do-that) 0))

By: deong

deong — Mon, 20 Jul 2009 15:20:48 +0000

It’s unfortunate that you have to remember to do this, but the reason you don’t see your code in the stack trace is that exceptions are nested, and you aren’t seeing a high enough level of the tree. The simple solution is to press “1″ at the stack trace you get in Slime. That doesn’t mean it’s not ugly, but it at least lets you work around a big part of the problem.

See http://w01fe.com/blog/2008/12/debugging-clojure-with-slime/ for more information.