[djur]

The language didn't have keyword arguments at the time it was originally created (nor did many other languages). The use of hashes as a way of simulating them was popular at the time (I've seen the same in Perl) but it was a good idea to eventually make them a full-fledged feature. It took a while to complete that transition without causing a serious backwards-incompatible disruption. Ruby has generally favored avoiding such things, which sometimes means finding some inelegant solutions.

[throwanem]

> it was a good idea to eventually make them a full-fledged feature

Why so?

[vidarh]

Because it provides a clearer way of enforcing calling conventions. Calling a method with the wrong keyword argument raises an error automatically. Calling a method with hash arguments the method expect replies on the method manually checking for unexpected keys. In Ruby as in other languages it was error prone.

[gls2ro]

Positional arguments creates a dependency on the position of the argument. And this is a cause of bugs when calling a method with the arguments in the wrong order.

Keyword arguments remove the depedency on the position.