From: dblack@...
Date: 2005-12-11T02:04:02+09:00
Subject: Re: lib for optional static typing

Hi --

On Sun, 11 Dec 2005, Daniel Berger wrote:

> Evan Webb mentioned that it would be possible to add a pseudo type
> system via Behaviors.  He may even have a working implementation for
> Sydney, but I'll have to double check.  It would look something like
> this:
>
> # pseudocode
> require "behavior/strongtyping"
>
> def foo(String x, y)
> end
>
> In this example, x must be a String, while y can be anything.  In
> effect, optional typing.

s/typing/ancestry-checking/

> I'm actually not sure if I want this, though.  I know I've supported it
> in the past, but I worry that Java/C/C++ programmers coming to Ruby,
> fearing the removal of the static typing training wheels, might adhere
> to this style too readily when it should only be used sparingly.

I think there are two main problems with this kind of thing: first,
that it could short-circuit people learning about how type actually
works in Ruby; and second, that it might discourage more Ruby-esque
program design.  It looks like it adds something to Ruby, but it
doesn't (since is_a? is already available), and in practice perhaps
subtracts something.


David

-- 
David A. Black
dblack@wobblini.net

"Ruby for Rails", forthcoming from Manning Publications, April 2006!