Improved stack traces

[Rich Hickey]

People frequently complain about Clojure's stack traces, and there are
now some enhancements in the master branch. In particular, there is a
new function in clojure.repl, pst, which prints a nicer stack trace of
the most recent (or a supplied) exception. It also has depth control.
pst is automatically available in the standard REPL.

The single-line initial messages should also be better.

Note as always that if you have a compilation/syntax error, the stack
can of course have nothing on it but the compiler logic itself. But
the file and line number of the code being compiled will, if
available, be in the single-line report.

Feedback welcome,

Rich

[Alan]

I assume I'm just clueless here, but the last commit I see at
http://github.com/richhickey/clojure is one from Stuart Halloway in
June. Where do I find this so I can try it out? Or, what version do I
have to tell leiningen I depend on - 1.2.0-snapshot, 1.3.0-snapshot,
or something like that?

[Nicolas Oury]

http://github.com/clojure/clojure

[Mike Hinchey]

I found when working on ticket 191 (dead now, I suppose) that counting the stack elements is not reliable, but = works to get rid of duplicates.  Below you can compare java's to your new function - the clojure has one duplicate element (the very last one).  Also, I find the "..." useful to know something is cut off.

root-cause is too generic of a name since it only strips out CompileException.

Will clojure.stacktrace be deprecated or patched to use this implementation?

My patch for 191 includes test code if you want to adjust it for this.

-Mike

user=> (.printStackTrace *e)

java.lang.Exception: Unable to resolve symbol: x in this context, compiling:(NO_SOURCE_FILE:0)

        at clojure.lang.Compiler.analyze(Compiler.java:5777)

        at clojure.lang.Compiler.analyze(Compiler.java:5723)

        at clojure.lang.Compiler.eval(Compiler.java:6002)

        at clojure.lang.Compiler.eval(Compiler.java:5965)

        at clojure.core$eval.invokeStatic(core.clj:2652)

        at clojure.core$eval.invoke(core.clj)

        at clojure.main$repl$read_eval_print__5766.invoke(main.clj:177)

        at clojure.main$repl$fn__5771.invoke(main.clj:198)

        at clojure.main$repl.doInvoke(main.clj:198)

        at clojure.lang.RestFn.invoke(RestFn.java:422)

        at clojure.main$repl_opt.invoke(main.clj:256)

        at clojure.main$main.doInvoke(main.clj:349)

        at clojure.lang.RestFn.invoke(RestFn.java:398)

        at clojure.lang.Var.invoke(Var.java:361)

        at clojure.lang.AFn.applyToHelper(AFn.java:159)

        at clojure.lang.Var.applyTo(Var.java:482)

        at clojure.main.main(main.java:37)

Caused by: java.lang.Exception: Unable to resolve symbol: x in this context

        at clojure.lang.Compiler.resolveIn(Compiler.java:6251)

        at clojure.lang.Compiler.resolve(Compiler.java:6195)

        at clojure.lang.Compiler.analyzeSymbol(Compiler.java:6158)

        at clojure.lang.Compiler.analyze(Compiler.java:5744)

        ... 16 more

nil

user=> (pst *e 40)

CompilerException java.lang.Exception: Unable to resolve symbol: x in this context, compiling:(NO_SOURCE_FILE:0)

        clojure.lang.Compiler.analyze (Compiler.java:5777)

        clojure.lang.Compiler.analyze (Compiler.java:5723)

        clojure.lang.Compiler.eval (Compiler.java:6002)

        clojure.lang.Compiler.eval (Compiler.java:5965)

        clojure.core/eval (core.clj:2652)

        clojure.core/eval (core.clj:-1)

        clojure.main/repl/read-eval-print--5766 (main.clj:177)

        clojure.main/repl/fn--5771 (main.clj:198)

        clojure.main/repl (main.clj:198)

        clojure.main/repl-opt (main.clj:256)

        clojure.main/main (main.clj:349)

        clojure.lang.Var.invoke (Var.java:361)

        clojure.lang.Var.applyTo (Var.java:482)

        clojure.main.main (main.java:37)

Caused by:

Exception Unable to resolve symbol: x in this context

        clojure.lang.Compiler.resolveIn (Compiler.java:6251)

        clojure.lang.Compiler.resolve (Compiler.java:6195)

        clojure.lang.Compiler.analyzeSymbol (Compiler.java:6158)

        clojure.lang.Compiler.analyze (Compiler.java:5744)

        clojure.lang.Compiler.analyze (Compiler.java:5723)

nil