[Info-vax] BLISS, was: Re: VMS on ARM, was: Re: Small x86-64 servers, PCs

[Chris Townley]

On 22/03/2021 18:18, John Dallman wrote:
> In article <i8gjluFeutU1 at mid.individual.net>, bill.gunshannon at gmail.com
> (Bill Gunshannon) wrote:
> 
>> I think the real problem isn't the limited number of people familiar
>> with them as much as the very limited number of people willing to
>> become familiar with them.
> 
> Having read the 1987 BLISS Reference Manual, I agree. Most young
> programmers don't want to learn assembly languages, and while BLISS is
> not an assembly language, it is - quite deliberately - rather close to
> the metal.
> 
> It is similar in intent and capability to BCPL ("Basic" in BCPL has
> nothing to do with the BASIC programming language), which uses the same
> kinds of data types. However, BCPL feels more like a higher-level
> language, while BLISS feels more like assembler. What make me think that?
> 
> 
> BLISS keywords are shown as all UPPERCASE in the manual, and while there
> is a hint that you can use lowercase, the point is not clearly addressed
> that I can find. This is hard on the eyes of people used to lowercase
> languages. This is only a question of what you're used to, but it's an
> initial barrier.
> 
> More assembler-like features include the "." operator, which is easier to
> miss than BCPL's similar "!" operator, and the rules on when you don't
> need it are more complex than they seem to need to be. The ability to
> have imperative, rather than advisory, register declarations, is also
> rather like assembler.
> 
> The syntax for data structures is powerful, but rather arcane, as well as
> having significant differences between architectures, It's more capable
> than the BCPL version, but unforgiving of mistakes. Much the same goes
> for linking, where BCPL is minimalist, while BLISS is built to cope with
> a rather gnarly multi-language environment.
> 
> BLISS is visibly built for a style of computing where memory is in very
> short supply, so packing stuff tightly and using bit-fields for
> everything is sensible. The world has changed, and simpler memory access
> patterns are needed for performance, until you get a long way down into
> small embedded systems.
> 
> The need to hand-optimise by choosing SELECT or CASE is something a
> compiler could readily take over.
> 
> Being an expression language is interesting, but hasn't been a compelling
> feature of any language that had it AFAIK. The syntax creates places
> where the presence or absence of a semi-colon makes a difference to
> semantics, and the compiler can't really warn the programmer. BLISS seems
> a very unforgiving language.
> 
> The manual uses lots of words explaining concepts that are just simpler
> in C-family languages. It seems to have been through several generations
> of enhancement, having started as a much simpler language which was
> enhanced without an overall plan. It all feels /primitive/ and I can see
> why the development of VMS for Alpha and Itanium used increasing amounts
> of C.
> 
> It was an interesting read, and showed me where Windows' Structured
> Exception Handling feature comes from, but I have no desire to do any
> BLISS programming. I've done a fair amount of assembler in my time, but
> writing assembler-like code is now only appropriate for quite specialised
> work.
> 
> John
> 
Wasn't BCPL the precursor to C?

Chris