[erlang-questions] where did my code come from?

David Goehrig <>
Tue Sep 13 21:44:30 CEST 2011


This is basically how most real world JavaScript applications already work, so it simply falls to building a nice distributed registry that can be universally queried. 

Erlang txt fields in DNS anyone?

Also since rebar already allows you to specify your dependencies as git tags, we already have a system that will automatically pull the specific source (or latest if unspecified) and build your application. 

Dave

-=-=-  -=-=-

On Sep 13, 2011, at 3:19 AM, Joe Armstrong <> wrote:

> I had an idea on my way to work ...
> 
> When you write code, you have *implicit* knowledge of where the
> external code comes from.
> 
> When I write the following:
> 
>     -module(foo).
>      ...
>     start() ->
>          X = lists:reverse(...),
>          Y = elib1_misc:zap(...)
>          Z = misultin:request(...)
>     ...
> 
> I "know" that lists is part of my local OTP install, elib1_misc is my
> own library installed
> in ~/code/elib2_1/ebin and misultin is an imported project stored in
> ~/imports/misultin
> I also know that my paths etc are setup so this code will work when I
> run the program.
> 
> The problem is the *nobody else* knows this.
> 
> I could tell the system like this:
> 
>    -module(foo).
> 
>    -location(lists,
> "https://github.com/erlang/otp/blob/dev/lib/stdlib/src/lists.erl").
>    -location(elib1_misc,
> "https://github.com/joearms/elib1/blob/master/lib/src/elib1_misc.erl").
>    -location(misultin,
> "https://github.com/ostinelli/misultin/blob/master/src/misultin.erl").
> 
>    ...
> 
> 
>   The location annotation give a *definitive source" for the module I
> am using in the module
> 
>    What could you do with this information?
> 
>    Answer - a lot - for starters
> 
>         - automatically check for "latest versions" of libraries
> download them when they change
>         - provide "who uses my code" feedback to the authors of the code
>         - publish (globally) lists of "definitive" versions of code
>         - recursive track and code dependencies (What do I mean)
>            when my system discovers that I use misultin - it
> downloads misultin.erl
>            misultin.erl will have location dependencies which I can
> follow, thus the libraries
>            that misultin calls can be fetched.
>         - automate code loading
> 
>    Most often this kind of "additional" information is kept "outside
> the program" by strictly
> annotating the program with the location dependencies we bring this
> information *into* the program
> in a form where it cannot be detached from the source code.
> 
>    Comments?
> 
>   /Joe
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