[Supermancho]

> Isn't that what documentation is for?

I would agree, if everything was documented. The issue at-hand is what is not explicitly documented. What constitutes a guard-worthy function? ie A pure javadoc without any notation about what the API does, is not sufficient.

[josevalim]

> The issue at-hand is what is not explicitly documented. What constitutes a guard-worthy function?

https://hexdocs.pm/elixir/1.15/patterns-and-guards.html#guar...

Plus the docs lists on the sidebar which custom functions are guards. Examples: https://hexdocs.pm/elixir/1.15/Integer.html#guards

[Supermancho]

The question was about why not what is allowed as a guard. Perhaps this was not clear amongst the noise.