From: elbows@... (Nathan Weston)
Date: 2003-11-17T10:23:18+09:00
Subject: Re: Strong Typing (Re: Managing metadata about attribute types)

Ryan Pavlik <rpav@mephle.com> wrote in message news:<20031107184353.002a2059.rpav@mephle.com>...
> 
> The problem is people seem to think that "implements String behavior"
> and "is a String" are two different things.   I'm not sure why.

I think in the ruby world, when people say "implements String
behavior", they really mean "implements some relevant subset of String
behavior".
This is where duck typing (which really isn't a type system at all,
IMO) becomes more flexible than type systems based on the class of an
object.

Whether this flexibility is a good thing is up for debate. Any type
system will catch some errors, and throw away some otherwise valid
programs. It's a question of freedom vs. safety, and the ruby
community mostly seems to come down on the side of freedom (at least
where programming languages are concerned).