General questions about the power of Erlang

Karel Van Oudheusden <>
Tue Dec 12 11:22:20 CET 2000

In response to Samuel Tardieu's email:

> Where did you read that Erlang was developed with Ada? (I'm very interested
> if you can give me such a reference, being an Erlang and Ada fan)

Ada and the functional paradigm were the main sources of inspiration for
developing Erlang.  (I got this from Bjarne Dackers thesis on Erlang).  I am
not saying that Erlang was developed with Ada.

> | I was wandering whether Erlang does behave correctly on for instance
> | Windows and if so, does it behave in the same manner as on Linux?
> What do you call "behave correctly"? Yes, Erlang works on both Windows on
> Linux, and does its duty :)
> | It is for me hard to believe that Erlang actually works well on Windows
> | platforms since we are talking here about (soft) real-time
> | applications.  Or am I missing something here?
> What prevents you from building soft real-time applications on Windows?
> "best-effort" will always be "best-effort", even on a pityful platform
> which offers no guarantee. I have even seen people doing soft real-time
> in Java, with zero guarantee of the scheduling policy.

It is exactly the scheduling which I am concerned about.  In Ada (what about
Erlang?) the programmer is for instance allowed to specify
certain scheduling desires.  These are however not similarly executed on the
different platforms (which is of course not surprising to some extent).  But in
DOS for instance, the programmer even has to explicitly add dispatching points
to his code for the scheduling to work with respect to the Ada reference manual
(cfr. GNU for DOS).  I am not going to go into detail on this here (perhaps a
personal email is more suitable since this concerns Ada).  My question was
whether similar (hard to debug) problems arise with Erlang in regards to the
scheduling of the various light weight processes.

Another question I have is the following.  Erlang has had a lot of success in
ATM switches.  Are these hard real-time (embedded) applications?  Is there a
good mathcing between the ATM hardware and the Erlang code?    Or is this the
same application domain as what Erlang is now made open source for: general
purpose programming (regardless of platform) for Internet applications?

I appologize for the perhaps unclear stated questions.
But any feedback is welcome (even if I expect something differently).


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