That's the point, Fortran today is a DSL for computational science, that's it and mainly what it focuses on today. It is not (if it ever was) a general programming language.
Colossal Cave Adventure (ADVENT) was written in Fortran.
Zork (aka Dungeon) was originally written in an obscure Lisp dialect invented at MIT, MDL; but Bob Supnik at DEC ported it into Fortran, and that version became widely distributed.
I used to work for a university, where the software which determined whether students had met all their degree requirements to graduate (such software is sometimes called a "degree audit tool"), was written in Fortran. Why? Well, it was a manual paper-based process, then one of the academics kindly volunteered to automate it for them. And he was one of the mathematics lecturers, and Fortran was his favourite language, so that's what he did it in. Some years later he retired, and without him the software became increasingly difficult to maintain – the university no doubt had some Fortran programmers in the physics/maths/engineering/etc departments, but the central administration's IT didn't. They ended up replacing it with some commercial off-the-shelf solution–no idea what that was written in, but almost certainly not Fortran.
All that to say I think Fortran can only claim to be what we call "general purpose" for a very limited window of time in the very early stages of computing.
In the early 1970s, almost every mainframe and minicomputer had a Fortran compiler available for it. Lisp was much rarer. Pascal had only just been invented and C was only just being invented. If you wanted your software to be as widely portable as possible, your choices were Fortran or Cobol, and no wonder why many preferred the former. (Especially if we are talking about software in academic/research environments, where Fortran was far more common than Cobol.)
This has little to do with Fortran and Lisp's respective years of introduction (1957 vs 1958), but rather how far they'd managed to spread in their first 15 years (almost everywhere for Fortran versus only to a narrow subset of academic research institutions for Lisp.)
> Fortran can only claim to be what we call "general purpose" for a very limited window of time in the very early stages of computing.
The timeframe in which Fortran saw “general purpose” use spanned at least a decade (maybe closer to two) and was after the “very early stages” (during which almost everything was in assembler - or even hand-assembled machine code - and portable code was basically unheard of)
FORTRAN was always dedicated to scientific computing, I don't believe it was ever used for system software, so it is a bit apples-to-oranges.
Early versions of PRIMOS used FORTRAN as a systems programming language, although later versions switched to Prime's proprietary PL/I dialect (PL/P) and Modula 2.
The reason for the somewhat unusual choice of FORTRAN as a systems programming language? Prime's founders were experienced FORTRAN programmers, so it was the natural choice for them, and in 1972 alternatives were far less established (C was only just being invented)
I think since f90, modern fortran still is a language well suited to that domain while removing a lot of the cruft (like requiring each line fit on a punch card, things like that, ugh), although the landscape of computing has changed dramatically since with scientists now being relegated to being a niche of computing as a whole. So fortran in that sense is more like a DSL today rather than one of the major use cases for computers, but by luck and history has a lineage with literally the oldest high level language. This is thus more like a historical accident than being something contingent for me. I think the fact that it is suited to computational science is a result, not a cause of it being for scientists (it was designed for us, we didn't find it and build it up or something like that), and the strict aliasing, well, I feel like that's just a lucky break that it was and thus easily optimizable...that and cray, HP et al did make supercomputers to run codes that scientists liked, and thus their architecture and optimizations worked well with fortran codes, and thus the development of both are clearly a coupled situation here.
Anyway, when it comes to today, modern fortran is still a strong language for computational science, specifically for numerical things like simulation and numerical solution and things like that, so when I say, "it is a DSL for computational science today," that encapsulates my opinion succinctly without having to go into the ramble about history, although history is mostly why it is the case today.
Two other usage patterns I can think of are large strings processing (think bioinformatics and genetics), and things with neural networks (which to be fair would be a natural fit for Fortran, if the libraries were not mainly developed in C++ and accessed from Python). Still, on the HPC facilities I use, number crunching in large arrays dominates used CPU time, and I would say about half of them are in Fortran.
It’s a shame I never really was in a situation to use it in a real program (also, you had to use PGI, which I have always found sub par), but I have tinkered with it over the years and it is very pleasant to use.