[erlang-questions] Generating Core Erlang -- Re: Dangers of generating a large erlang module

Anthony Ramine <>
Mon Sep 30 10:07:18 CEST 2013


Hello Tom,

The compiler `erlc` automatically pass from_core to the compile module if the file extension is .core.

Regards,

Le 29 sept. 2013 à 23:01, Tom Murphy a écrit :

> There's also just:
> 
> erlc +to_core foo.erl
> erlc +from_core foo.core
> 
> Tom Murphy
> 
> 
> On Sun, Sep 29, 2013 at 11:59 AM, Loïc Hoguin <> wrote:
> On 09/29/2013 08:24 PM, Ivan uemlianin wrote:
> That's what I've just done :D  Core Erlang looks very verbose but quite
> regular & probably not difficult to generate.
> 
> My questions now are:
> - are there any libraries "out there" for generating Core Erlang, or do
> we all roll our own?
> 
> Look at the cerl module. It's just a matter of generating the proper structure using those functions.
> 
> 
> - how would one use compile:file or compile:forms with core erlang? I
> haven't been able to find any documentation (haven't read Richard
> Carlsson's Introduction paper yet).
> 
> Do read it. But to answer that question, compile:forms with from_core option.
> 
> Many thanks
> 
> Ivan
> 
> --
> festina lente
> 
> 
> On 29 Sep 2013, at 18:36, Erik Søe Sørensen <
> <mailto:>> wrote:
> 
> Core Erlang is an intermediate  representation in the Erlang compiler
> - but also (afaik) a fairly well-defined/public one and one that is
> stable.
> I don't think you'll find much in the vein of tutorials. Try getting
> erlc to output the intermediate format, though, for a small program
> similar to what you'll be using it for.
> 
> Den 29/09/2013 19.20 skrev "Ivan uemlianin" <
> <mailto:>>:
> 
> 
>     Thanks! I think I'll try and head in that direction. I've had a
>     few goes at other methods (db lookup etc) and they're much slower
>     than this "dynamic hardcoding"). I'll sniff around for Core Erlang
>     tutorials.
> 
>     Best wishes
> 
>     Ivan
> 
> 
>     --
>     festina lente
> 
> 
>     On 29 Sep 2013, at 17:48, Erik Søe Sørensen <
>     <mailto:>> wrote:
> 
>     A thing which I discovered recently (in connection with
>     mochiglobal) is that compiling code containing large binaries, or
>     large amounts of binaries,  is quite memory-intensive. As I
>     recall it, the numbers were ~64 bytes of RAM per byte in a binary
>     metal; twice as much if on a 64 bit emulator.
>     Which means that if you want to compile modules containing (in
>     sum) multimegabyte binaries, doing so from Erlang source or from
>     full Erlang AST is a no-go.  Iirc, it is feasible if starting
>     from Core Erlang.
>     /Erik
> 
>     Den 29/09/2013 12.50 skrev "Ivan Uemlianin" <
>     <mailto:>>:
> 
> 
>         Dear Anthony
> 
>         Thanks for your comment.
> 
>         Yes, that's exactly what the generated module is doing.  The
>         generated module has a single function with many clauses like
>         this:
> 
>             f(<<"trigger", Rest/binary) -> ...
> 
>         This is why (as far as I can work out) the generated code has
>         to be so big.
> 
>         I prefer the idea of generating and loading code to, say,
>         updating a database table, because it seems faster and less
>         likely to lead to bottlenecks.
> 
>         Best wishes
> 
>         Ivan
> 
> 
>         On 29/09/2013 11:38, Anthony Ramine wrote:
> 
>             Hello Ivan,
> 
>             Out of curiosity, what does it look like?
> 
>             Pattern matching on literal values in Erlang is done with
>             a binary search over the sorted list of patterns, I am
>             not sure this would play well with your use case even if
>             the compilation didn't bring the VM down.
> 
>             Regards,
> 
>             Le 29 sept. 2013 à 11:29, Ivan Uemlianin a écrit :
> 
>                 All goes well on small test files, but the files I
>                 want to use IRL are relatively large --- around
>                 120,000 lines.
> 
> 
> 
>         --
>         ==============================__==============================
> 
>         Ivan A. Uemlianin PhD
>         Llaisdy
>         Speech Technology Research and Development
> 
>          <mailto:>
>         www.llaisdy.com <http://www.llaisdy.com>
>         llaisdy.wordpress.com <http://llaisdy.wordpress.com>
>         github.com/llaisdy <http://github.com/llaisdy>
>         www.linkedin.com/in/__ivanuemlianin
>         <http://www.linkedin.com/in/ivanuemlianin>
> 
>                                 festina lente
>         ==============================__==============================
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> 
> -- 
> Loïc Hoguin
> Erlang Cowboy
> Nine Nines
> http://ninenines.eu
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-- 
Anthony Ramine



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