Guards Guards – small gotcha in Elixir guard expressions • Hacker News Board

Guards Guards – small gotcha in Elixir guard expressions

#1

Post by hauleth » Sun, Jun 28, 2026, 9:24 AM UTC

Guards Guards – small gotcha in Elixir guard expressions
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Re: Guards Guards – small gotcha in Elixir guard expressions

#2

Post by turtleyacht » Sun, Jun 28, 2026, 12:27 PM UTC

Elixir does not short-circuit its if-then either:

  if false or true do
    IO.puts("did not short-circuit (?)")
  end

Maybe because `if' is a macro, the whole expression is sent in for evaluation:

https://elixir-lang.readthedocs.io/en/latest/intro/5.html#if...

Re: Guards Guards – small gotcha in Elixir guard expressions

#3

Post by hauleth » Sun, Jul 05, 2026, 7:56 AM UTC

turtleyacht wrote: post #2

Elixir does not short-circuit its if-then either: if false or true do IO.puts("did not short-circuit (?)") end Maybe because `if' is a macro, the whole expression is sent in for evaluation: https://elixir-lang.readthedocs.io/en/latest/intro/5.html#if...

What do you mean there? What is not short-circuited there?

Re: Guards Guards – small gotcha in Elixir guard expressions

#4

Post by turtleyacht » Sun, Jul 12, 2026, 11:57 PM UTC

hauleth wrote: post #3

turtleyacht wrote: post #2

Elixir does not short-circuit its if-then either: if false or true do IO.puts("did not short-circuit (?)") end Maybe because `if' is a macro, the whole expression is sent in for evaluation: https://elixir-lang.readthedocs.io/en/latest/intro/5.html#if...

What do you mean there? What is not short-circuited there?

The whole thing `false or true' is sent in for evaluation, so if there is a side-effect function that returns `true', it is executed too. Because Elixir treats it as a macro and not short-circuit.