Re: 4th generation languages

[w-ckaras@ix.netcom.com(Walter William Karas)]

In <32668924.175A@sn.no> Aron Felix Gurski <agurski@sn.no> writes: 
...
>	4th generation: usually proprietary languages that include FOCUS,
the 
>	                language used by SAS Institute's products, etc.
and 
>	                more recent languages like xBase (I'd classify
APL as
>	                4th generation -- these languages tended to have 
>	                reserved words that performed *huge* operations,
like
>	                statistical analyses, in one statement)
...

I don't know much about it, but I think there's a bit more to this
topic.  4th gen. languages to many mean non-procedural languages.
For example, a statement in a data base query language specifies
a subset of a table or a new table created from existing tables.
But it doesn't specify how or when it should be done.  There
are "rule-based" languages that consist of "if this, then that"
type statments that aren't executed sequentially.  They're activated
by triggering their initial condition, directly or indirectly.
As best as I can understand it, in a 3rd gen. language, you tell
the computer how to do something.  In a 4th gen. language, you
tell the computer what something is, and it figures out how
(and when) to make it and how to use it.

You probably want to read something about Prolog.  I've also
heard Fuzzy Logic mentioned in the same breath as 4th gen.
languages.