Kevin's Weblog

A continutation from where I left off last night...

The mind-boggling nature of this (optional interface features without ugly type checks or exceptions) isn't the fact that you can do it. Perl and Smalltalk programmers are immediately familiar with this form of polymorphism (interface polymorphism) (and the associated runtime errors when you screw up). Lispers would say, "Variables don't (shouldn't) have types, values have types". However, strongly typed languages like Java and C++ usually lock you into inheritance polymorphism. (Despite Java's use of the term "interface", it does not imply the same flexibility.) The magic here is interface polymorphism with compile-time type checking.

At some point I'll have to think more about type-inferring languages like OCaml and how exactly things work there. I'm not sure if that compiler will allow you the same flexibility and safety as the C++ template technique.

(Side note to all this: When did I become a language geek?)