Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!cs.utexas.edu!uunet!tektronix!tekcrl!tekgvs!toma
From: toma@tekgvs.LABS.TEK.COM (Tom Almy)
Newsgroups: comp.lang.forth
Subject: Re: Multiple Stacks
Message-ID: <5220@tekgvs.LABS.TEK.COM>
Date: 25 May 89 17:53:31 GMT
References: <442@mtk.UUCP>
Reply-To: toma@tekgvs.LABS.TEK.COM (Tom Almy)
Distribution: usa
Organization: Tektronix, Inc., Beaverton,  OR.
Lines: 19

In article <442@mtk.UUCP> marmar@mtk.UUCP (Mark Martino) writes:
>When is it useful to implement additional stacks?  What characteristics
>of a programming problem suggest that multiple stacks would be a good
>solution?
>
Well, STOIC (a variant of Forth) had separate "Loop" and "Return" stacks.
That way you could access values on the Return stack (which, like Forth,
is commonly used as a second parameter stack) easily from within a
loop structure.

I have used the 8087 internal floating point stack in Forth.  It's
actually easier to use floating point when the values are on a separate
stack since you don't have to figure out how to (for instance) swap
a float (is it 32 or 64 bits?) with an integer (is it 16 or 32 bits?).

I have also seen string stacks, but I find them inefficient.

Tom Almy
toma@tekgvs.labs.tek.com