Then we say "the argument occurs in both positive and negative
positions" or "the argument occurs in both covariant and contravariant
positions". There doesn't seem to be a shorter name. I want to note that
this kind of thing drives OOP crazy.
i recall this paper being of some help:-)
http:/
On Thu, Apr 05, 2007 at 06:26:17PM -0300, Felipe Almeida Lessa wrote:
> I know that types like
>
> >data T = T (T -> T)
>
> are inhabitated by things other than bottom (like id or \_ ->
> undefined), but can it be useful for *anything*?
Yes. In particular, types like those can produce an explic
On 4/5/07, Albert Y. C. Lai <[EMAIL PROTECTED]> wrote:
Dan Weston wrote:
> What is it called if it's both?
Then we say "the argument occurs in both positive and negative
positions" or "the argument occurs in both covariant and contravariant
positions". There doesn't seem to be a shorter name. I
Dan Weston wrote:
What is it called if it's both?
Then we say "the argument occurs in both positive and negative
positions" or "the argument occurs in both covariant and contravariant
positions". There doesn't seem to be a shorter name. I want to note that
this kind of thing drives OOP crazy
On Wed, Apr 04, 2007 at 02:57:06PM -0700, Dan Weston wrote:
> What is it called if it's both? Is this even legal in Haskell? It seems
> as though this would not be a grounded type, going on forever in both
> directions.
I guess "negative datatype" is being a bit loose with terminology; the
funct
What is it called if it's both? Is this even legal in Haskell? It seems
as though this would not be a grounded type, going on forever in both
directions.
Dan
Stefan O'Rear wrote:
On Wed, Apr 04, 2007 at 01:36:18PM -0700, Michael Vanier wrote:
For those of us who aren't type theorists: What's
On Wed, Apr 04, 2007 at 01:36:18PM -0700, Michael Vanier wrote:
> For those of us who aren't type theorists: What's a "negative datatype"?
Negative isn't the usual term; we mostly call them 'contravariantly
recursive' data types, due to CT influence. Anyways the thing to note
is that the value ap
For those of us who aren't type theorists: What's a "negative datatype"?
Mike
Edsko de Vries wrote:
Hey,
It is well-known that negative datatypes can be used to encode
recursion, without actually explicitly using recursion. As a little
exercise, I set out to define the fixpoint combinator usin
On Wed, Apr 04, 2007 at 07:39:24PM +0100, Edsko de Vries wrote:
> Hey,
>
> It is well-known that negative datatypes can be used to encode
> recursion, without actually explicitly using recursion. As a little
> exercise, I set out to define the fixpoint combinator using negative
> datatypes. I thin
Hey,
It is well-known that negative datatypes can be used to encode
recursion, without actually explicitly using recursion. As a little
exercise, I set out to define the fixpoint combinator using negative
datatypes. I think the result is kinda cool :) Comments are welcome :)
Edsko
{-
Def
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