Re: [stack] Notation for typed arrays in Cat

On Fri, Apr 4, 2008 at 1:25 PM, William Tanksley, Jr
<[email protected]> wrote:
> Christopher Diggins <[email protected]> wrote:
> > I am again playing with the idea of how to introduce typed arrays in to
> Cat.
> > The following is the notation that I prefer, but I am concerned about
> > the confusion of ['a] meaning a list of 'a in types, and [a] meaning a
> > quotation in the code:
>
> Factor uses {} for arrays and [] for quotations (and lists). It does
> seem to me that there should be a way to denote different type
> treatment, especially if the two entities behave differently in other
> ways (for example, lists could be conceptually sequential, while
> arrays could be conceptually parallel; thus, "i" would work on lists,
> while the combinators we're talking about would be expected to execute
> an array).
> > Another syntax I am seriously considering is:
> > uncons : ('a* -> 'a* 'a)
> > cons : ('a* 'a -> 'a*)
> > empty : ('a* -> 'a* bool)
> > count : ('a* -> 'a* int)
>
> This nicely expresses "an unknown number of elements of this single
> type", which is (I believe) what you mean by "array". What would an
> array literal look like in Cat, though? It _should_ (one would think)
> be possible to tell the difference between an untyped list and a typed
> array reasonably quickly.

Sorry for the confusion I am using the terms "array" and "list"
interchangeably. In Cat a quotation is not a list (or array or
whatever). There is also no built-in syntax for writing list literals
in Cat. A quotation is [1 2 3]. A list is generated using the "list"
instruction. E.g. "[1 2 3] list". We can overload "(", ")" and "," to
construct lists like (1, 2, 3) but this is just syntactic sugar.

What I am proposing that all lists in Cat will become either lists of
"any" (e.g. dynamically typed) or can be lists of some specific type
(e.g. int*, or ('A -> 'B)*)

I hope this clarifies things

Thanks for your feedback!
- Christopher