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From: bakul@netcom.com (Bakul Shah)
Subject: Re: BETA questions
Message-ID: <bakulD7EsHr.F8G@netcom.com>
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Date: Fri, 21 Apr 1995 23:41:51 GMT
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carroll@quadriga.cis.udel.edu (Mark C. Chu-Carroll) writes:

>(beta patterns are closures. But the overwhelming majority of the
>time, they don't need to be treated with the full generality of a
>closure - they can be treated as simple procedures.)

A minor quibble:

Closures to the first approximation, may be?  Consider:

    counter: (# i:@integer enter i do i+1->i; inner exit i #);  
    k1: @counter;
    k2: @counter (# do i-2 -> i #);
    12->k1;	{set k1.i to 13 }
    12->k2;	{set k1.i to 11 }
    k1->v;	{v equals 14}
    k2->v;	{v equals 10}

I can see how to *model* this using closures but it is hard
for me to see a one-to-one correspondence between closures
and patterns.

>In principle, Beta programs should perform *extremely* well: Beta is
>an extremely easy language to analyze, and it lacks the features of
>most OO languages that make it hard to optimize (like dynamically
>bound procedure calls).

Agreed that they should perform very well but don't you have to
dynamically bind virtual patterns?  I don't know Beta too well
so please excuse my mistakes.

Bakul Shah <bakul@netcom.com>