Re: Logical equivalence of simple and complex types under the relational model?

A long time ago, in a galaxy far, far away, neo55592_at_hotmail.com (Neo) wrote:
>> In common lisp the ultimate type is 't' (short for true)
>> which all values are a members of.
>
> Does lisp have NULLs? Is it considered a value? How do lisp programs
> persist their data?

It has two main sorts of NULLs:

1. The value, NIL, which is essentially the "opposite" of T, the "true" value.
2. The function NULL, which more analagous to the SQL concept; in that case, you aren't comparing values, but merely asking if a particular one is NIL.

There have been three traditional models for "persistance" of data in Lisp:

1. Save an image of the environment and thereby recall everything upon restart;
2. Serialize data into files that may be serially loaded;
3. Connect to a DBMS and use it to "persist" data. -- let name="cbbrowne" and tld="gmail.com" in String.concat "_at_" [name;tld];; http://www3.sympatico.ca/cbbrowne/oses.html Language was designed by people for their own use, so presumably it [parsing] shouldn't be too difficult for them to do with whatever algorithm they have. -- Bill Martin (6.863 lecture, spring 1980)