From: Doug McIlroy <doug@cs.dartmouth.edu>
To: <tuhs@tuhs.org>, <doug@cs.dartmouth.edu>, <arnold@skeeve.com>
Subject: Re: [TUHS] BTL summer employees
Date: Sun, 02 Aug 2020 13:13:07 -0400 [thread overview]
Message-ID: <202008021713.072HD7Ba120877@tahoe.cs.Dartmouth.EDU> (raw)
In-Reply-To: <202008021357.072DvOYo024549@freefriends.org>
>> Even high-school employees could make lasting contributions. I am
>> indebted to Steve for a technique he conceived during his first summer
>> assignment: using macro definitions as if they were units of associative
>> memory. This view of macros stimulated previously undreamed-of uses.
> Can you give some examples of what this looked like?
One useless, but telling, program of mine was a Turing-machine
simulator. Tape cells were represented by macros that contained
a symbol and the (macro) names of adjacent cells. New cells
could be generated as needed, with names derived from a counter.
A natural way to store the state-transition table (I forget
how it was actually done) would be as macros whose names
are the concatenation of state and symbol names.
Path-compression as used in union-find algorithms originated
in a macroprocessor implementation by Bob Morris. Each graph
node was represented by a macro that pointed to or toward
the root of a tree spanning its graph component.
Doug
next prev parent reply other threads:[~2020-08-03 9:42 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-02 13:40 Doug McIlroy
2020-08-02 13:57 ` arnold
2020-08-02 17:13 ` Doug McIlroy [this message]
2020-08-03 9:24 ` arnold
2020-08-02 15:12 ` Robert Diamond
2020-08-02 19:05 ` Jon Steinhart
2020-08-03 5:14 ` Heinz Lycklama
2020-08-03 12:55 ` John P. Linderman
2020-08-03 16:26 ` Jon Steinhart
2020-08-10 0:48 ` Dave Horsfall
2020-08-10 0:53 ` Larry McVoy
2020-08-10 6:33 ` Lars Brinkhoff
2020-08-10 12:53 Noel Chiappa
2020-08-10 13:21 ` Lars Brinkhoff
2020-08-10 14:02 Noel Chiappa
2020-08-10 17:08 ` Lawrence Stewart
2020-08-10 18:13 ` Lars Brinkhoff
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