From: Alexander Kellett <ruby-lists@...>
Date: 2005-01-09T07:25:51+09:00
Subject: Re: Type inference in ruby

On Jan 8, 2005, at 9:28 PM, Trevor Andrade wrote:
> You cannot define how to add integers in Ruby and in fact you cannot 
> even define
> integers themselves.  Integers are low level constructs that must be 
> built
> into the language.  [snip]

its possible to redefine integer additions in ruby.
however yes you're correct in saying that its not possible
to redefine the integer constructor. (tho i'm working
on making that possible ;))

> There is only one thing wrong with type inference and that is that new
> methods can be defined at runtime in Ruby which means it is possible 
> that an
> object does not know how to respond at compile time to a message but 
> it does
> know how to respond at runtime.  However I think this scenario happens 
> very
> rarely and if it was happening the programmer could just turn off type
> inference.

i think personally that test suites should guide typing metadata.
if a testcase only has a test for a single data type. then the
assumption can be made that the type itself is required. if however
it has a test for two different data types each of which have a given
method, which happens to be part of an included module, to ease test
case writing it should be possible via comment hints to show the
inferrer / document-type-metadata-hinter that it is duck typed not
static typed.

Alex