I dont think there is something wrong with that once you think about what is a Null Element (or identity) in a group that is represented by a set of elements and a function:

Integer, + => 0

Float, + => 0.0

Array, add => []

Hash, merge => {}

and so on.

I think maybe we can debate the operations/functions, but they make sense. For Integer in some ways you can define almost all other operations that you commonly use based on the addition.

So while nil is an object when trying to find a representation in other group I find it logical or expected.

Also Ruby will not automatically try to coerce nil when not asked to do so

like for example 0 + nil will throw an error.

Integers support both addition and multiplication and taking maximum and minimums, and a few other semi-group operations. Do you want to define different Null elements for all of them?

No, I don't want to define a representation for Null to all possible combinations of a set and a function/operation. That can be done by each developer if they see it fit and of the operations they want to have this.

But, for me, it makes sense to have a default representation for Null (that it is not automatically coerced—only if the developer explicitly asks for it) for one of the most common operations in that specific group.

Of course since it's Ruby you can just monkey patch those to_s methods to do whatever the hell you want, confounding anyone else working on your codebase.

I love using Ruby when I'm the only one who will ever have to look at or touch it.

> the to_s is "", to_i is 0, to_f is 0.0, to_a is [], to_h is {}

I somehow can't help reading that as some sort of high school sports-cheer: "Gimme an S to the quote to the I to the oh to the F to the zero! Goooo Rubies!"

Those conversions make sense though. They all mean empty or null. It's what I would expect from a language like Ruby.

Integer 0 means empty with respect to a particular operation (addition) but is not empty with respect to all operations (ex. multiplication)

Indeed. One's greatest strength is also their greatest weakness.