Are aliased functions optimized in Erlang

Question

Say i have a function that is exported from a module, but the modules uses the function many times.

So i wrote an alias, because i'm lazy when i code.

-export([get_toolkit/0]).

get_toolkit() -> 
    ... code ... code ... 
    ... code ... code ... 
    ... code ... code ... 
    {ok, Thing}.

tk() -> get_toolkit().

Does the compiler optimizes aliases ?

Thanks

Answer 1

I think it will cost you one indirection. I say this because I took this code

-module(testit).
-export([get_toolkit/0, long/0, short/0]).

get_toolkit() -> 
    _ = lists:seq(1,100),
    {ok, thing}.

tk() -> 
   get_toolkit().

long() ->
    get_toolkit(),
    {ok, thing2}.

short() ->
    tk(),
    {ok, thing3}.

and generated the ASM via erlc -S testit.erl which gave me

SNIP

{function, tk, 0, 4}.
  {label,3}.
    {line,[{location,"testit.erl",8}]}.
    {func_info,{atom,testit},{atom,tk},0}.
  {label,4}.
    {call_only,0,{f,2}}.


{function, long, 0, 6}.
  {label,5}.
    {line,[{location,"testit.erl",11}]}.
    {func_info,{atom,testit},{atom,long},0}.
  {label,6}.
    {allocate,0,0}.
    {line,[{location,"testit.erl",12}]}.
    {call,0,{f,2}}.
    {move,{literal,{ok,thing2}},{x,0}}.
    {deallocate,0}.
    return.


{function, short, 0, 8}.
  {label,7}.
    {line,[{location,"testit.erl",15}]}.
    {func_info,{atom,testit},{atom,short},0}.
  {label,8}.
    {allocate,0,0}.
    {line,[{location,"testit.erl",16}]}.
    {call,0,{f,4}}.
    {move,{literal,{ok,thing3}},{x,0}}.
    {deallocate,0}.
    return.

• The first function listed in the snip-it is the "short-hand" function, tk/0.
• the second is the long function which calls get_toolkit/0,
• the third is the short function which uses the tk/0 short-hand

the ASM shows that the last function (the one that uses tk/0 ) calls tk/0 ({call, 0, {f, 4}}) which in turn calls get_toolkit/0 ({call, 0, {f,2}}). The function which uses get_toolkit/0 directly calls get_toolkit/0 directly ({call, 0, {f,2}}).

So, I think that there is no optimization applied.

Also, I did some time-tests which seemed to support this hypothesis ;)