[comp.sys.apple] interpreters, compilers, P-systems

dlyons@Apple.COM (David Lyons) (06/02/89)

In article <6230031@hpindda.HP.COM> tribby@hpindda.HP.COM (David Tribby) writes:
[...]
>I hate to disagree with one of my favorite Apple experts, but the big
>difference between interpreted BASIC and the P-system is the amount of
>"digesting" done before execution of the program.

I don't think we actually disagree--it just sounds like it.

You're talking about *the* P-system with UCSD Pascal, and I'm just talking
about pseudo-code systems in general.

>                                                    With BASIC, the exact
>structure of the source program must be maintained because the user
>may modify it. Very little is done, except tokenization of key words.

But more *could* be done in an interpreted BASIC.  It just isn't in Applesoft.

>With P-code Pascal, the source code is actually compiled. During execution
>there is no need to search for variables since they will be at fixed
>locations. Yes, the P-code must be interpreted, but it is much closer to 
>machine code than BASIC tokens.

Right, but it's all a matter of degree.  While I would certainly classify
UCSD Pascal as compiled and Applesoft as interpreted, these are just at
different ends of the "lump."  Applesoft isn't purely interpreted (it's
tokenized) and UCSD Pascal isn't purely compiled (it's compiled into a
P-code that, at least on an Apple II, is interpreted).

>--Dave Tribby
>        ARPA: tribby%hpda@hplabs.HP.COM   UUCP: hplabs!hpda!tribby

 --Dave Lyons, Apple Computer, Inc.          |   DAL Systems
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