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This proposal is subsumed under the first phase of <a href="/display/design/Error+Handling" data-linked-resource-id="950768" data-linked-resource-type="page" data-linked-resource-default-alias="Error Handling" data-base-url="http://dev.clojure.org">Error Handling</a>

Goals:

<ul>
	<li>Provide useful stacktraces to end-users</li>
	<li>Provide stacktraces-as-data to library developers</li>
</ul>

Approach:

Stacktrace handling can be divided into three parts: collecting and parsing the exception data, filtering/transforming that data as appropriate for Clojure, and then rendering that data according to some design.

To facilitate steps 2 and 3 for Clojure itself and also for other library developers, we propose to first parse exceptions into Clojure data structures and to provide this data as input to the filtering/transforming and rendering phases.

The data-based approach is used by <a href="http://github.com/mmcgrana/clj-stacktrace">clj-stacktrace</a>.

clj-stactrace, clojure.repl, and clojure.stacktrace all have <a href="http://gist.github.com/649282">different takes</a> on the formatting aspect of stacktrace presentation.

Issues:
<ul>
	<li>Why is :annon-fn three-valued (true, false, and missing)?</li>
	<li>Is it possible to get full paths instead of filenames under the :file key?</li>
	<li>Default display format for stacktraces for script and REPL exceptions</li>
	<li>Details of exception data representation, especially strings vs. non-strings and how to represent different types of trace elements like methods, def'd fns, and closures
	<ul>
		<li>SDH: I think names of classes, methods, etc. should be symbols (as opposed to strings). Haven't looked to see what current impls do so this may be moot.</li>
	</ul>
	</li>
</ul>