Different closure between Erlang and Elixir

Hello everyone,

Here is some erlang code I wanted to translate to Elixir… here is a simple example in the console.

$ erl
Erlang/OTP 22 [erts-10.4.4] [source] [64-bit] [smp:8:8] [ds:8:8:10] [async-threads:1] [hipe]

Eshell V10.4.4  (abort with ^G)
1> Pid=self().                            
<0.82.0>
2> Ref = monitor(process, Pid).              
#Ref<0.2147538226.2721841158.105393>
3> receive                                
3> {'DOWN', Ref, process, Pid, Why} -> Why
3> end.

and here is the Elixir version I came up with…

$ iex
Erlang/OTP 22 [erts-10.4.4] [source] [64-bit] [smp:8:8] [ds:8:8:10] [async-threads:1] [hipe]

Interactive Elixir (1.9.1) - press Ctrl+C to exit (type h() ENTER for help)
iex(1)> pid = self()
#PID<0.108.0>
iex(2)> ref = Process.monitor(pid)
#Reference<0.417878796.1379926020.235519>
iex(3)> receive do
...(3)> {:DOWN, ref, :process, pid, why} -> why            
...(3)> end
warning: variable "pid" is unused (if the variable is not meant to be used, prefix it with an underscore)
  iex:4

warning: variable "ref" is unused (if the variable is not meant to be used, prefix it with an underscore)
  iex:4

Code is quite similar, but in the Elixir version, ref and pid are not seen by the receive block, while the Erlang version will match on a ‘DOWN’ message where Ref and Pid are set.

Why is that different?

Thanks for taking time