Path: utzoo!utgpu!jarvis.csri.toronto.edu!clyde.concordia.ca!uunet!willett!ForthNet
From: ForthNet@willett.UUCP (ForthNet articles from GEnie)
Newsgroups: comp.lang.forth
Subject: Category 10,  Topic 35
Message-ID: <183.UUL1.3#5129@willett.UUCP>
Date: 5 Jan 90 16:04:48 GMT
Organization: Latest Link in ForthNet Chain
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Category 10,  Topic 35
Message 74        Fri Dec 22, 1989
R.BERKEY [Robert]            at 07:42 PST

  To: Roedy Green

 RG> 7.0340 2>R
 RG> Remove the editor's note on why DO parms are backwards...

I agree, even if for a different reason.

What the 2>R rationale doesn't quite say is that DO has been implemented on
pre-1983 system's as:

: DO   COMPILE 2>R ; IMMEDIATE

with the parameter's for DO having been set long before this 1981
implementation was noticed.

Upon learning of 2>R , I at first thought that the parameters were backwards,
a kludge to save a few bytes by not having a (DO) .  Later I realized that
they aren't backwards.  Looking at how the numbers appear in memory, this
version maintains the double number. Another way to describe this is that 2>R
can be implemented using 2@ and 2! .

If the rationale given in BASIS was the reason for this order of parameters
now being standardized, I'd be opposed to it: because standardizing a word
designed for obsolete loops that speed optimize on DO is standardizing
garbage.

Anyway, thanks for your comments about the 2>R rationale.

Robert Berkey


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