[erlang-questions] Fear and Loathing in Programming La La Land

Joe Armstrong <>
Thu Apr 12 09:03:57 CEST 2012


On Thu, Apr 12, 2012 at 4:58 AM, Richard O'Keefe <> wrote:
>
> On 11/04/2012, at 10:20 PM, Jan Burse wrote:
>
>> General Questions:
>>
>> - Would it be allowed to make a Erlang language realization?
>

That's ok - there is a trademark restriction as regards use of the name "Erlang"
the reason is we don't want to damage the "brand" ie we don't want there to be
implementations of Erlang that are manifestly buggy etc.

Implementing everything from scratch would require major effort - the usual
path is to implement a backend. You use standard Erlang to compile the Beam code
then write a Beam backend.

There are Beam backends for the JVM and JavaScript and there is work in progress
for JIT'ing beam code.

Beam code is essentially "abstract register machine" code - so it
actually involves
yet another transformation step before it can be executed.

The erlang compiler from erlang to beam code does all the pattern matching etc.
so what's left is pretty low level - things like bignums, garbage
collection, process memory management and scheduling are pushed into
the runtime.

Implementing Erlang is ticky because, for an implementer it's a mixture of
language and OS issues. Implementing non-blocking I/O for example
involves lots of nasty low-level code etc.

> There have been at least three other very-close-to-Erlang implementations
> that saw the light of day:  EtoS (Erlang to Scheme) and EC by Maurice
> Castro of SERC at RMIT (back when there _was_ a SERC).  See
> http://erlang.org/pipermail/erlang-questions/2004-July/012838.html
> about EC.  Hmm; there was also GERL (Geoff's Erlang).  I've no idea
> what Laurie Brown and Maurice Castro are up to these days.
>
> I'm aware of a couple of other partial implementations which were never
> shipped.  At various times I've had copies of GERL and ETOS but would
> have a hard time finding them now; the Real Thing is so hard to keep up
> with...
>
>> - Any legal problems with copyright or so?
>
> Doesn't look like it.
>
>> - Any ways to certify it, i.e. test suite etc.?

We don't certify implementations - but there is a large test suite bundled in
the distribution

Cheers

/Joe


>
> That I can't help with.
>
>
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