7 Nov
2017
7 Nov
'17
4:18 a.m.
On Mon, Nov 6, 2017 at 2:46 PM, Steve Johnson <scj(a)yaccman.com> wrote:
I had a senior moment when I sent out my posting about
the origin of void
*. The person in question
was Larry Rossler, not Charlie Roberts -- apologies to both!
Larry was active in the ANSI committee, so he had a bully pulpit for
suggesting this change...
About Bliss, there certainly was a bit of a competition for a while
between C and Bliss, and Bliss wasn't such a bad language. But the
technology behind it was pretty ugly. You had to compile PDP-11 programs
on a Dec System 20, which shut out a large percentage of the people who
might have been interested. And they took a very relaxed stance of
pointer aliasing -- basically, the compiler assumed that no two pointers
pointed to the same thing unless you turned on a flag in which case it
assume all pointers pointed to all other pointers. This would not have
worked well for system code...
Pascal was a much more serious competitor -- it was much easier to teach
75 people in a room how to program in Pascal than in C, and P-code was a
reasonable portability mechanism. The differences have been much discussed
in this forum so I won't restart that thread again...
At one point about 15 years after C has pretty much won over Bliss, I gave
a job interview to a programmer at Dec who was responsible for maintaining
50 million lines of bliss. I've rarely met anyone who was more determined
to change jobs!
I've seen the signature "Bliss is ignorance" :)
Warner
Steve
----- Original Message -----
From:
"Warner Losh" <imp(a)bsdimp.com>
To:
<arnold(a)skeeve.com>
Cc:
"TUHS main list" <tuhs(a)minnie.tuhs.org>, "Paul Ruizendaal"
<pnr(a)planet.nl>
Sent:
Mon, 6 Nov 2017 08:02:53 -0700
Subject:
Re: [TUHS] origins of void*
On Mon, Nov 6, 2017 at 12:24 AM, <arnold(a)skeeve.com> wrote:
Paul Ruizendaal <pnr(a)planet.nl> wrote:
I thought there'd also been some influences from BLISS... DEC did much of
their system programming in BLISS along side the MACRO-{11,32,20}.... Not
exactly a strongly typed language, but another entry in the higher level
language category that C was competing against.
Warner
>> In the 4BSD era there was caddr_t, which
I think was used for pretty
>> much the same purposes.
>
> Only for kernel code. I am pretty sure caddr_t wasn't used in
user-land
code.
Ah, thanks for pointing that out, I had not realised that and it helps
explain some things. But why wasn’t caddr_t used for user-land code:
usage in the signature of e.g. write() would have made sense, right?
It's clear from K&R 1 that char* served as both pointer to string and
generic pointer to memory. That's not unreasonable, since, in some sense,
"memory is just bytes". So user-land code didn't need caddr_t. I also
suspect that caddr_t came into being with the effort to port Unix off
the PDP-11 and the weight of Unix practice before then had been to make
do with char*.
I think it helps to remember the evolutionary processes that were
happening
in the '70s. High level languages had caught on for application code
(FORTRAN and COBOL in the US, Algol in Europe) but the weight of existing
practice for *systems coding* (operating systems and utilities) had been
to use assembly language. Multics proved that you could write an OS in
a high level language, but Multics itself (at that time) wasn't a success.
So when C came along in the mid-'70s, strong typing had essentially been
absent from systems programming. With time and experience, along with
the recognition in the general CS world that strong typing was valuable,
C also started to evolve in that direction.