110 sats \ 2 replies \ @Undergotten 24 Aug 2023 \ parent \ on: What old school tech needs to have a big comeback? tech
"Any sufficiently complicated C or Fortran program contains an ad hoc, informally-specified, bug-ridden, slow implementation of half of Common Lisp."
Ok, now I'm intrigued. Can someone ELI5? I'd dive deeper into this statement, but I need to go to work.
ELI5-ing this topic is tough without also ELI5-ing a bunch of obscure parts of computer science. But I'll give it a shot anyways.
If you are writing a big program in a language like C or Fortran, it will get harder-and-harder to make changes as the program gets bigger-and-bigger. Common Lisp provides powerful ways to manage complexity in an efficient way.
C/Fortran requires you to do a lot of things manually. As the program gets bigger, a C/Fortran program requires more work from the programmer. Common Lisp automates certain kinds of programming tasks, and it provides ways for the programmer to automate many other programming tasks.
C/Fortran requires you to stop running the program entirely in order to change the program's code. Common Lisp will let you change your program's code without stopping your program.
But C/Fortran programmers will not re-write their program in Common Lisp, when their C/Fortran code becomes too complex. Instead, they will add a scripting language to their complex C/Fortran program. Such scripting languages are what Greenspun's Tenth Rule summarizes:
- ad-hoc: Those scripting languages are intended to be used for a narrow range of tasks.
- informally-specified: There is minimal thought put into their design before starting work on them.
- bug-ridden: They are written in C/Fortran, so all the problems of writing complex software in C/Fortran apply to making the scripting language too. A bug in the scripting language will seem like a bug in your scripts, so the bug becomes tough to fix.
- slow: They are always made using an interpreter, which means they are inherently slower than using a compiler (e.g. C, Fortran, and Common Lisp).
- half of Common Lisp: Common Lisp is a large, complex language; and it was written by experts in the design of programming languages. When you are making an ad-hoc scripting language, it isn't worth it to re-create all of the features of Common Lisp. Half of Common Lisp usually feels like it is enough, but eventually you realize you need more, which requires even more complex C/Fortran code.
I don't know if that's ELI5. I can explain each part in more detail if you'd like. But I can't guarantee that those explanations will be ELI5.
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That was awesome. Above and beyond ELI5. Thank you.
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