[erlang-questions] How to interpret lambda stacktrace?

Maxim Treskin <>
Wed Feb 17 17:04:42 CET 2010


Thank you very much, Robert!

On 17 February 2010 21:49, Robert Virding <> wrote:
> The first part of the name, -amm_handle_ev/3- in your case is the
> function name/arity in which the fun or comprehension is defined.
> Then:
>
> - for a fun this is followed by -fun- and the index of the fun within
> the defining function. So "-fun-5-" means the fifth fun within the
> function, as a whole.
>
> - for a comprehension it is "-lc$^" and the index of the comprehension
> within the module. It can be either "lc", "blc" or "lbc" depending on
> type of comprehension. The "$^" has no significance as such.
>
> These are basically just funny names which are most likely unique. Two
> important points:
>
> - NO this naming is not defined anywhere, it is purely internal.
> - NO there is no guarantee that it won't be changed in the future.
>
> So use it for info but be warned.
>
> Robert
>
> On 17 February 2010 05:33, Maxim Treskin <> wrote:
>> Hello
>>
>> Sometime I have writing code with nested lambda-functions and
>> list-comprehensions.
>> If this code contains, I have such stacktraces in crash report:
>>
>>    exception exit: {function_clause,
>>                        [{asg_alt,'-amm_handle_ev/3-fun-5-',
>>                             [undefined,#Fun<asg_alt.15.120311847>,
>>                              pass]},
>>                         {asg_alt,'-amm_handle_ev/3-lc$^3/1-3-',2},
>>                         {asg_alt,'-amm_handle_ev/3-lc$^3/1-3-',2},
>>                         {asg_alt,amm_handle_ev,3},
>>                         {asg_pd,state_ready,2},
>>                         {gen_fsm,handle_msg,7},
>>                         {proc_lib,init_p_do_apply,3}]}
>>
>> Is there any way to understand which of lambda crashes? So, when
>> function contains '-lc$' I can say that this is list-comprehension
>> function, '/3' -  arity of top function, but what means '^3/1-3-' and
>> '-fun-5-' ? Is this values has some relation with order of its
>> definition or not?
>>
>> Thank you
>>
>> --
>> Maxim Treskin
>>
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>



-- 
Maxim Treskin


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