Excerpts from Ben Walton's message of Wed Aug 19 19:57:25 -0700 2009: > Excerpts from Carl Worth's message of Wed Aug 19 20:31:12 -0400 2009: > > > [*] Totally off-topic: This is one of the things about "dynamically > > typed" languages that I've never been able to wrap my brain around. I > > really like that with static typing I can trust the compiler to help > > me be very thorough if I make a type change like this, (and catch all > > the cases before shipping any code). ... > The term you'll see bandied about in ruby circles/books/etc is 'duck > typing' which coming from strongly typed languages is definitely > something that takes some getting used to. Basically, instead of > caring about the type of the object, you case about what the object > does. If it walks like a duck and quacks like a duck, treat it like a > duck.
Yes, I understand that just fine. But two points: 1. That's not actually helping in the current case where we're trying to do simple things like '+' and the distinction between Set and Array is causing problems. (See the patch where we're having to add .to_a and Set.new to coerce things.) So, here, at least things are falling down. So somehow something in ruby isn't living up to the concept here. > Then, you'll see many examples where there is code like: > > raise SomeException, "blah" unless someobject.respond_to?(:somemethod) > > Your code doesn't care _what kind_ of object it gets as long as it > knows _how_ to talk to it. 2. Even with the "duck typing" I'd still like to express this constraint in a way that is decidable statically. I've definitely failed as a programmer if a user sees a runtime exception like that. Sytems with sophisticated runtimes are very interesting to me. It's just discouraging to me that so many such systems fail to actually help me avoid problems like this before the user is running my code. > Personally, I really like this. Ruby isn't perfect by any stretch, > but of all the languages I've used, it's hands down the most fun to > write. That could still be the case for me here. I haven't tried much with it yet, so I don't have any strong opinion there yet. :-) -Carl
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