Presented by way of being an interesting link, and the educational nature of reading the best arguments in favor of something. I haven't done anything in concatenative programming in about 20 years, since I left math class and didn't need my HP 48G anymore.
So, for instance, let's elicit an error using Ghostscript, a freely available and efficient PostScript interpreter:
$ gs
GPL Ghostscript 9.27 (2019-04-04)
...
/f { /hello g } def
Therefore, when I then invoke "f" via:
GS>f
Error: /undefined in g
GS<1>pstack
/hello
[0]: https://groups.google.com/d/msg/rec.arts.int-fiction/HNtntxC...
PostScript is a real programming language and can be used for many things (especially graphics). I also wrote a JSON parser in PostScript (see message <[email protected]> on comp.lang.postscript), and then someone else post their JSON parser in PostScript too.
I think PostScript isn't such a good protocol or document format, but it is good as a programming language. It is what I might use if I want to make a diagram (but unfortunately Ghostscript cannot produce SVG output; it can output PDF though, as well as many raster formats).
Someone was unsure how useful would be the JSON parser I wrote in PostScript, but if you want to print some diagram based on data in JSON format, then it can be helpful.
(I could implement Z-machine in Forth too if I wanted to do, but I have not done so yet because I have other things to do; I don't know if I might do so in future or not. I could implement Z-machine in any programming language with byte arrays, including assembly language (I started but haven't finished one in 6502).)
is a fractal fern. This is page description, but not in the normal way that it's used. Compare the output in a PS or PDF viewer with the source code which is under 1.5K.
But I think maybe you meant in the sense of "in the real world", and I can't think of any examples. Prefixing some postscript to a document to manipulate that file is something it can be suited for, rather than using an external language to do so.
https://www.cs.bham.ac.uk/research/projects/poplog/primer/#s...
Functions that return several results, implicit parameters, open stack, etc. It's a lot of fun.
Rather, the key characteristic is that there is an important implicit feature available, namely the stack (or, as for example in the case of PostScript, several stacks), by which arguments can be passed along.
As a consequence, you get a form of compositionality of language elements that is not available in languages that lack this feature: A language element may consume, change and create entities on the stack, and the next language element can pick them up implicitly.
This often allows very concise and elegant code, and can also be interpreted very efficiently.