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From: ok@quintus.uucp (Richard A. O'Keefe)
Newsgroups: comp.lang.ada
Subject: Re: Garbage Collection
Message-ID: <864@quintus.UUCP>
Date: 14 Dec 88 06:40:47 GMT
References: <6702@june.cs.washington.edu> <3865@hubcap.UUCP>
Sender: news@quintus.UUCP
Reply-To: ok@quintus.UUCP (Richard A. O'Keefe)
Organization: Quintus Computer Systems, Inc.
List-Id: <comp.lang.ada>

In article <3865@hubcap.UUCP> billwolf@hubcap.clemson.edu writes:
>    Basically, I charge garbage collection with the same crime that
>    the GOTO was charged with: its sole function is to facilitate
>    UNDISCIPLINED programming.  From Tremblay and Sorenson, 1985:

This is completely back-to-front.  Doing your own storage management
is like doing your own stack management instead of using procedure calls.
If you want to compare garbage collection with a control structure,
compare it with resursive procedures.

>    If this charge can be successfully prosecuted, then garbage
>    collection will face the same penalty: the total elimination 
>    of the facility, in favor of a more disciplined environment.

I think it would be very hard to accuse functional programming languages
like ML of providing an _un_disciplined environment.  Yet automatic storage
control is vital to them.  A word about the history of ML may make this
clearer.  ML was originally the MetaLanguage of Edinburgh LCF, a system
for doing proofs about computations.  It is strongly typed, because it
was important that anything the system claimed to be a proof should be a
valid proof.  There is a basic set of proof-forming operations which are
known to be valid.  The language cannot permit changes to elements of a
data structure, otherwise the arguments to a proof might be changed after
the proof was constructed, rendering it invalid.  "deallocate" simply
doesn't make sense in that kind of environment.  Storage management is
particularly easy in a language without side effects to data structures.