I was creating simple RPN calculator function, but I stumbled upon a problem in matching functions in guards. Code looks like so: def compute_RPN_expr(value, stack) when is_number(value), do: [value | stack] def compute_RPN_expr(operator, stack) when operator in [&+/2, &-/2, &*/2, &//2] do [a, …

One important reason is hot code reloading and the distributed kind of Erlang/Elixir programs: If you are running code on multiple nodes, then they both have separate versions of the functions that might be executed (and if you try to upgrade both nodes to a new version, they are not guaranteed to u…

In general you can’t compare functions for equality. So even if it were syntactically allowed, it wouldn’t make sense semantically. Instead you should use atoms as operators and map them to functions.

Why so? This would work like a comparing function pointers in C - checking their address. I’m kinda expecting doing most operations on normal variables will work on functions too. So, for me it makes sense if I’m passing function f as argument and inside some function I’m checking if I actually pass…

There are no function pointers in elixir. &+/2 is different in every module you write this. Also, even though both of the following functions are obviously producing the same result for their respective domains, you can’t computationally compare them for equality without doing manual prooves: def …

I don’t want to prove that function A is equals to function B. I Just want to compare them by address, e.g. iex(1)> a = &Float.round(&1, &2) &Float.round/2 iex(2)> b = &Float.round(&2, &1) #Function<12.127694169/2 in :erl_eval.expr/5> Those 2 functions above aren’t the same, even when they’re doi…

@jgonet There are not many cases in which you actually touch the Erlang/BEAM low-level stuff directly or have to keep them in mind (most of the time, Elixir’s abstractions are very leak-free). However, I would recommend watching Solid Ground because it will give you a good high-level foundation of u…

The BEAM Book: Understanding the Erlang Runtime System is a good resource for looking at the internals of how the BEAM itself works. Decisions and capabilities like the one you’re describing are gonna either be present or absent on the basis of the BEAM itself, Elixir just gets compiled to BEAM byte…

[image] NobbZ: apply(:erlang, op, [a, b]) Why is :erlang the module in MFA.

You could use Kernel, but those just forward to the erlang implementations anyways: elixir/lib/elixir/lib/kernel.ex at 8ca85ed2a82019df1a2acf3238f24a56370464bb · elixir-lang/elixir · GitHub