I’m new to Elixir, and from what I read heavy use of recursion is mandatory. With that in mind, I look at this simple blink example I found: defmodule FlightController do use Application @blink_duration 150 # ms @led_pin 18 @gpio_on 1 @gpio_off 0 def start(_type, _args) do {:ok, p…

Elixir / Beam supports tail-call optimization. Tail call In computer science, a tail call is a subroutine call performed as the final action of a procedure. If the target of a tail is the same subroutine, the subroutine is said to be tail recursive, which is a special case of direct recu…

The BEAM uses Tail Call Optimization (TCO) to avoid blowing the stack. As an example: def fac(1), do: 1 def fac(n), do: n * fac(n -1) is not TCO because the recursive can only be done when it is the last operation of the function. In the fac function above it needs to keep the frame to do the mul…

So then TCO just turns the recursive function into a loop. Thanks!

Yep, in fact otp has an idiom for running a self-calling recursive loop in its own process, in such a way that it can respond to messages from other processes and keep track of some internal state: that’s really all a GenServer is. However it has extra tooling to help keep it alive and respawn to a …

Actually the tail call optimisation is done for all last calls not just recursive calls. It is sometimes called last-call optimisation. So you can write: defmodule Foo do def bar() do baz() end def baz() do bar() end end which will happily recurse forever without building stack. I…

Joe Armstrong: [erlang-questions] Tail call optimization The correct name for the optimization used in Erlang is “last call optimization”.

Endless recursion

Questions & Help Questions

CptnKirk December 7, 2017, 9:35pm 2

Elixir / Beam supports tail-call optimization.