I guess it would make only sense to have it part of the core if it was a simple type, that could use +/-/* operators. If we kept the need to use Decimal.add and friends , this can very well be a separate lib.

It’s currently being discussed in the core team if we should add the Decimal library to the elixir standard library. It may or may not happen.

The main reason the calendar types were added to core elixir was to have a common set of data structure all the libraries could use and work on. For decimal types we don’t have this need since afaik there is only one decimal library in the ecosystem.

If you want Decimal added to the standard library you need to argue what the benefits would be.

That’s not really an argument, except that it’s popular. The webserver cowboy and dependencies are even more popular, should they also be included in core elixir?

Every extra module in core elixir puts extra burden on the elixir core team. That means less new features and less bug fixes for the existing code in the standard library. The more code the community can take care of the better and with the dependency handling in mix and package management in hex it’s not that much extra work to use a dependency.