[TUHS] Re: What would early alternatives to C have been?

[Clem Cole <clemc@ccc.com>]

[-- Attachment #1: Type: text/plain, Size: 3132 bytes --]

Marc - check out OpenSIMH( https://opensimh.org)
Check out over 40 different simulators including the I7000 which
supports IBM 701,7010,7070,7080, 7090 - https://opensimh.org/simulators/


ᐧ

On Mon, Mar 10, 2025 at 7:12 PM Marc Rochkind <mrochkind@gmail.com> wrote:

> This thread started to be about what I thought were system programming
> languages (e.g., C, BLISS) and seems to have meandered into a general
> discussion of languages that were around in the 1960s and 1970s, so, what
> the heck, I'll add my own story.
>
> PL/0 is an education programming language introduced in the book, *Algorithms
> + Data Structures = Programs*, by Niklaus Wirth in 1976. It's a great
> language for teaching compiler writing because it contains interesting
> concepts, such as recursive functions, yet isn't overly complicated. I
> wrote a PL/0 compiler for the IBM 701 (
> https://github.com/MarcRochkind/pl0compiler).
>
> Yeah, that's not a misprint. I wrote perhaps the world's only 701 emulator
> (https://www.mrochkind.com/mrochkind/a-701.html), and my PL/0 compiler
> runs on it. Unfortunately, I can't verify that the compiled code runs on an
> actual 701, since I'm sure there haven't been any in operation for many
> decades. For those of you who haven't had the pleasure, programming the 701
> is really hard. It had no index registers, and the sign bit didn't
> participate in shifts. Still, my compiler compiles full-blown PL/0.
>
> So there! ;-)
>
> Marc Rochkind
>
> On Mon, Mar 10, 2025 at 2:49 PM Bakul Shah via TUHS <tuhs@tuhs.org> wrote:
>
>> Perhaps the interviewer was looking for something dumb like the following
>> and not a full RD parser?
>>
>> int count = 0;
>> while (*cp) {
>>         char c = *cp++;
>>         count += c == '(' ? 1 : c == ')' ? -1 : 0;
>>         if (count < 0) return -1; // FAIL: one too many )
>> }
>> if (count > 0) return -1; // FAIL: too many (
>> return 0; // SUCCESS
>>
>> Though this will fall apart if you also want to also balance braces &/or
>> brackets and must catch invalid cases like "(..[..)..]"!
>>
>> > On Mar 10, 2025, at 8:19 AM, John Cowan <cowan@ccil.org> wrote:
>> >
>> > I was working at the whiteboard during a job interview once. I had been
>> asked to write a function to report if its input had balanced parentheses.
>> No problem: I wrote an RD parser in Python (which I prefer for
>> whiteboarding) to detect balance and return True if the parse was
>> successful and False if EOF was reached.
>> >
>> > I was starting to write some tests when the interviewer interrupted me.
>> >
>> > "What is that?"
>> >
>> > "It's a recursive descent parser. It detects if the input is
>> well-formed."
>> >
>> > Blank look.
>> >
>> > I started to walk him through the code.
>> >
>> > He interrupted me. "Excuse me, I'll be back in a few minutes."
>> >
>> > Long wait, maybe 15-20 minutes. Someone else comes in. "Thank you, the
>> recruiter will get back to you." That's the last I hear from them.
>>
>>
>
> --
> Subscribe to my Photo-of-the-Week emails at my website mrochkind.com.
>

[-- Attachment #2: Type: text/html, Size: 5058 bytes --]