Re: list algebra
From: mAsterdam <mAsterdam_at_vrijdag.org>
Date: Wed, 30 Jun 2004 11:59:53 +0200
Message-ID: <40e28f19$0$6968$e4fe514c_at_news.xs4all.nl>
>
> Ah, I see your point.
>
> To my mind, this is simply a typing question. If I have a simple
> variable of type <any>, then I can put any value of any type in
> there, but I can't do any operations on it because <any> has
> no operations.
>
> In this way of thinking, every list is homogeneous; it is simply
> homogeneous as some upper bound of the union of the types
> of all the elements.
Date: Wed, 30 Jun 2004 11:59:53 +0200
Message-ID: <40e28f19$0$6968$e4fe514c_at_news.xs4all.nl>
Marshall Spight wrote:
> mAsterdam wrote:
>>Marshall Spight wrote: >>>>You plan to use any lists or some particular kind of lists ? >>> >>>Any list. >> >>Heterogeneous lists look like they can create a lot of >>(for the order problem unnecessary) complications >>when looking at them in a relational framework. >>Homogeneous lists (all elements of one type only) would >>suffice for the 'order' problem sec - or am I just seeing ghosts?
>
> Ah, I see your point.
>
> To my mind, this is simply a typing question. If I have a simple
> variable of type <any>, then I can put any value of any type in
> there, but I can't do any operations on it because <any> has
> no operations.
>
> In this way of thinking, every list is homogeneous; it is simply
> homogeneous as some upper bound of the union of the types
> of all the elements.
I like it. A list by definition homogeneous. The somewhat explosive differentiation is pushed to 'type'.
It won't suit widely spread ideas on the meaning of the term list, so it must be stated.
http://www.swif.uniba.it/lei/foldop/foldoc.cgi?list <quote>
A data structure holding many values, possibly of different types, which is usually accessed sequentially, working from the head to to the end of the tail - an "ordered list". This contrasts with a (one-dimensional) array, any element of which can be accessed equally quickly. </quote>
Hm... I see some entries emerging in the glossary's todo list. Received on Wed Jun 30 2004 - 11:59:53 CEST