[erlang-questions] Why is Erlang what it is?

Mats Cronqvist <>
Fri Dec 15 11:20:20 CET 2006


Dominic Williams wrote:
> Hi,
> 
> I'm going to be the devil's advocate here - I have a strong preference 
> for dynamic typing, but I just want to make sure we get our arguments 
> right...
> 
> Mats Cronqvist wrote:
> 
>>  but a few years ago i did a study on erlang-related bug reports in
>>  our live product. the conclusion was that once we get to system test,
>>  we find essentially no more type-related bugs.
> 
> This goes to show that with adequate testing, one can make reliable 
> systems with dynamic typing.

   it is of course a truism that with "adequate" testing you can build anything 
with anything. heck, given another 10 years of testing bill gates might prove 
that you can build a reliable OS in C++ :>

> It seems to me this reasoning, although, valuable, does not refute the 
> argument that static typing might have /saved/ you a lot of testing effort.

   well, maybe i wasn't clear enough. what i'm saying is that once the designer 
checks in the code (i.e. it has passed his internal testing) and it goes to 
system test, we find very few "type bugs" (where a "type bug" is something that 
would have been found by a type checker).
   i conclude that type checking would have saved us no system testing time.

     mats



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