From: dot@dotat.at (Tony Finch)
Subject: [TUHS] Array index history
Date: Wed, 7 Jun 2017 15:58:50 +0100 [thread overview]
Message-ID: <alpine.DEB.2.11.1706071524340.21595@grey.csi.cam.ac.uk> (raw)
In-Reply-To: <20170607135004.GB7802@yeono.kjorling.se>
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Michael Kjörling <michael at kjorling.se> wrote:
>
> And https://www.bell-labs.com/usr/dmr/www/bcpl.pdf page 11 (PDF page
> 14) says:
>
> > 4.7 Vector Applications
> > /.../
> > Semantics: A vector is represented by a pointer to a consecutive
> > group of words which are the elements of the vector. The pointer
> > points to the zeroth element.
That syntax is quite different from the later BCPL that I'm familiar with.
http://www.cl.cam.ac.uk/~mr10/bcplman.pdf
It has a ! indirection operator which can be both unary and binary, as in
old BCPL new BCPL C
lv x @x &x
rv ptr !ptr *ptr
ptr*[i] ptr!i ptr[i]
Richards' 1969 paper uses a down-arrow for binary !
You can use "manifest" constants for laying out a structure, e.g.
MANIFEST { car; cdr; }
declares car and cdr to have values 0 and 1. This lets you do struct-style
indirection using the same operator as for array indexing, like in this
function definition:
LET cadr(p) = p!cdr!car;
When I saw how ->integ is used in the 6th Edition kernel it felt very BCPL
to me.
Tony.
--
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next prev parent reply other threads:[~2017-06-07 14:58 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CAH_OBiewwwS6kbdWKUO-j3v=Do+Y9AzBn4ZkyVic7LOJN5WX7w@mail.gmail.com>
[not found] ` <CAH_OBid5q-YeB6UYeOfjW68s3nb3TX_icC5dFMapfo=7_q5DUQ@mail.gmail.com>
[not found] ` <CAH_OBideJeNGiiys=VOEYcU1cffSg+6zDOD39HOU74vumQF0kA@mail.gmail.com>
[not found] ` <CAH_OBie_+dQXOC2OaZii5K=j1Ljmv-OvAVXvyypoLJ10jaysWA@mail.gmail.com>
[not found] ` <CAH_OBidXd1Lpgp8ttM3sWLfXDT0ms5EGAzEjPH9QkY+bXyev2w@mail.gmail.com>
[not found] ` <CAH_OBifge2RrwcDvSV46gwLAc0wHVtH++gdMBhXi-x8C0a_2jw@mail.gmail.com>
[not found] ` <CAH_OBic3MTy-20C_T2ciT2x+EjNZvXR2PJ0OzB0qRp1gd2OL-g@mail.gmail.com>
2017-06-07 12:56 ` shawn wilson
2017-06-07 13:16 ` Ron Natalie
2017-06-07 13:20 ` arnold
2017-06-07 13:50 ` Michael Kjörling
2017-06-07 14:02 ` arnold
2017-06-08 11:28 ` Christian Neukirchen
2017-06-08 14:56 ` shawn wilson
2017-06-07 14:58 ` Tony Finch [this message]
2017-06-07 23:57 ` Dave Horsfall
2017-06-07 16:31 ` Lyndon Nerenberg
2017-06-08 0:47 ` Bakul Shah
2017-06-07 17:59 ` Tim Bradshaw
2017-06-07 18:29 ` Clem Cole
2017-06-07 18:46 ` Arthur Krewat
2017-06-07 19:03 ` Ron Natalie
2017-06-07 19:15 ` Arthur Krewat
2017-06-07 19:49 ` Ron Natalie
2017-06-08 1:58 ` ARJANEN Loïc Jean David
2017-06-08 13:49 ` Random832
2017-06-08 13:55 ` Arthur Krewat
2017-06-08 18:41 ` Tim Bradshaw
2017-06-08 2:45 ` Robert Swierczek
2017-06-08 4:05 ` Dave Horsfall
2017-06-08 6:19 ` Peter Jeremy
2017-06-08 7:02 ` Dave Horsfall
2017-06-08 13:53 ` Ron Natalie
2017-06-08 2:27 Doug McIlroy
2017-06-08 12:49 ` William Cheswick
2017-06-08 12:56 ` Michael Kjörling
2017-06-08 13:45 ` Dan Cross
2017-06-08 13:57 ` Ron Natalie
2017-06-10 21:08 ` Nemo
2017-06-08 15:04 ` Dave Horsfall
2017-06-08 15:09 ` William Pechter
2017-06-08 16:53 ` Steve Nickolas
2017-06-08 20:17 ` Larry McVoy
2017-06-09 0:03 ` Greg 'groggy' Lehey
2017-06-08 9:16 Richard Tobin
[not found] <mailman.882.1496854900.3779.tuhs@minnie.tuhs.org>
2017-06-08 18:20 ` David
2017-06-08 18:55 ` Ron Natalie
2017-06-09 21:21 ` Steve Johnson
2017-06-09 21:52 ` Arthur Krewat
2017-06-08 22:29 ` Johnny Billquist
2017-06-08 23:16 ` Ron Natalie
2017-06-08 23:41 ` Steve Nickolas
2017-06-09 15:12 ` Random832
2017-06-09 16:30 ` Ron Natalie
2017-06-09 0:21 ` Johnny Billquist
2017-06-09 0:25 ` Pete Turnbull
2017-06-09 1:19 ` Toby Thain
2017-06-09 2:14 ` Pete Turnbull
[not found] <mailman.890.1496953026.3779.tuhs@minnie.tuhs.org>
2017-06-08 22:28 ` Johnny Billquist
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