Re: dynamic vs. static typing

[Matt Hellige <address@hidden>]

[Joe Marshall <jrm@ccs.neu.edu>]
> Matt Hellige <matt@immute.net> writes:
> 
> > The reason I don't think we're seeing any great examples of TRULY
> > heterogeneous lists of completely abstract, unconstrained values is
> > that, as has been amply pointed out, such a thing is literally,
> > exactly and provably no more useful than (and, in fact, equivalent to)
> > a natural number. I don't know how to make that more clear.
> 
> The reason there are no `TRULY heterogeneous lists' is because it is
> always possible to create a discriminated union type that covers all
> elements.
> 
> It is especially pointless if you fold all operations on objects
> into the object interface itself.
> 
> But if you take the view that certain operations (like intensional
> equivalence or intensional identity) are independent of the objects,
> then the notion of heterogeneous lists becomes much more interesting.
> Permutation, for example, becomes possible.
> 

Can you explain why a designer would want to take this view? Does it
have some benefits that I've missed?

Matt

-- 
Matt Hellige                  matt@immute.net
http://matt.immute.net