Simon Taylor wrote:
> In article <1116283418.903814.273940_at_f14g2000cwb.googlegroups.com>, Mikito Harakiri wrote:
>>Jan Hidders wrote:
>>>
>>>The way that function symbols are interpreted in Prolog and what gives
>>>them their expressive power in combination with recursion is more like
>>>what you would call a tuple constructor. So a term like f(x,y)
>>>represents a binary tuple with fields x and y and a label f that
>>>distinguishes it from g(x,y). So a better analogue would be user-defined
>>>record types where the type system allows arbitrary deep nesting or
>>>recursive types.
>>
>>I'm not sure I see the significance of nesting, although I seem to get
>>a feeling why genericity of record type is a big deal.
>
> Nesting is not significant; it's allowing data structures to express
> choice that increases the expressive power.
I tend to disagree. Choice by itself can always be flattened, but
arbitrary deep nesting cannot, so it does matter for the expressive
power of the query language.
Received on Tue May 17 2005 - 11:31:59 CDT
