What decides the name of a module?

[Matthias Lang]

Roger Price writes:
 > What decides the name of a module?

the -module directive

 > Is the module name specified by the declaration -module(.) or implied by
 > the source file name? - or are there two different notions of "module"
 > that I am confusing?

The convention is that the module name matches the file name. If you
want to break that convention, you have to provide your own code
loading mechanism. 

Example: let's insist on putting a module called "roger" in a file
called "rabbit.erl". One way to load it is:

  9> compile:file("rabbit.erl").                   
  {ok,roger}
  10> f(), {ok, Bin} = file:read_file("rabbit.beam").
  {ok,<<70,79,82,49,...>>}
  11> code:load_binary("roger", "rabbit.beam", Bin). 
  {module,"roger"}

Matthias