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Path: utzoo!linus!security!genrad!grkermit!masscomp!clyde!floyd!vax135!ukc!rde
From: rde@ukc.UUCP
Newsgroups: net.lang
Subject: Re: Untyped languages? (BCPL)
Message-ID: <4050@ukc.UUCP>
Date: Thu, 12-Jan-84 11:51:19 EST
Article-I.D.: ukc.4050
Posted: Thu Jan 12 11:51:19 1984
Date-Received: Sat, 14-Jan-84 02:57:53 EST
References: <489@tekchips.UUCP> <2465@azure.UUCP> <224@kobold.UUCP>
Organization: Computing Lab. Kent University, England
Lines: 42


    Some more information about BCPL.  Since the mid 1970s, the operator
'%'  (percent)  has  been  supported  by  virtually all compilers.  This
provides a partial solution to the byte addressing problem.

    x%y addresses the byte at offset y from word address x

    (on a VAX, this would be x*4+y, get it?)

    The byte  addressing  problems  are  still  there,  but  they  cause
relatively  few  problems.   They only rear their ugly head when calling
operating systems, and when evaluating addresses using  the  LV  (or  @)
address  operator.   Indexing  is  done  by using the scaling operations
provided by most hardware these days (e.g. index mode on a VAX).  I have
written a 4.1BSD compiler, and the code isn't bad at all (even though  I
say it myself).

    About  CPL.   The  project  died  because there were too many people
involved, not all in the same geographical location,  with  insufficient
time to spend on development.

    The  language isn't so very different from C, although (as one would
expect) it is rather less terse.  There are more control structures  (no
increased  functionality,  but  it probably makes programs more readable
than some of  the  awful  for(....)  constructs  I  have  seen).   Minor
differences   include  things  like  multiple  assignment  that  creates
temporaries if there would be interaction....

     a, b := b, a

actually swaps a and b!

     If anyone is really interested, I could dig out more....

       Bob Eager

       Computing Laboratory,
       University of Kent,
       Canterbury, UK.
       CT2 7NF.

   (secretary, BCPL User Group!!)