| Your comments are clear enough; they're just mistaken. Lisp dialects generally do not support mathematical functions, despite supporting the functional-programming idiom, which is inspired by mathematical functions. Rather, they support procedures, which in most Lisps are called "functions". In Scheme, however, the Lisp they chose for the course, they are called "procedures", an intentional choice to avoid creating precisely the kind of confusion you are experiencing. Lisp "functions", like procedures in most other languages, can fail to terminate, can raise an error, can have side effects, and can depend on mutable state. Mathematical functions cannot do any of these things. If they could, it wouldn't make much sense to take their Laplace transforms! The five chapters of SICP (I recommend http://sarabander.github.io/sicp/html/index.xhtml) are: - 1 Building Abstractions with Procedures - 2 Building Abstractions with Data - 3 Modularity, Objects, and State - 4 Metalinguistic Abstraction - 5 Computing with Register Machines — ⁂ — You said: > Nothing in my comment is about modelling anything to do with electronics in software. You are mistaken about that. The part of your comment that is about modelling something to do with electronics in software is the part where you replied to a comment saying: > ... four "deep dives" into the four "languages of engineering." There were four 15-unit courses, each about one of these "languages": > - 6.001: Structure and Interpretation of Computer Programs (the "procedural" language, led by Abelson and Sussman) > - 6.002: Circuits and Electronics ("structural" language) > - 6.003: Signals and Systems ("functional" language) > - 6.004: Computation Structures ("architectural" language) Your comment in reply said: > Lisp (...) can hardly be called "procedural". The core material of SICP revolves around (...) concepts that (...) have far more to do with "structure", "architecture" and "functionality" [sic] than with "procedure". That is, you were explicitly asserting that the core material of SICP was concerned with "structure", "architecture", and "functions" in the sense of the core material of those courses, rather than only or even primarily procedural abstraction. However, two of those four courses—specifically, 6.002 and 6.004—were concerned almost exclusively with modeling electronics. (An awful lot of the "systems" in 6.003 are also electronic, but that's beside the point.) However, as you know, 6.001, SICP, and Lisp are concerned exclusively with modeling things in software. Modeling electronics in software is a reasonable thing to do, and Lisp is a reasonable medium to do it in, but you need to understand the structural, architectural, and (at least for analog electronics) functional angles on the electronics in order to do that. None of that is part of SICP or 6.001, and Lisp is not a reasonable medium for describing electronic systems from at least the structural and functional angles. You need schematics, pole-zero diagrams, and Bode plots. If you remembered what you studied in that course 20+ years ago this would be obvious to you. |
> - 1 Building Abstractions with Procedures
Where Abelson, Sussman & Sussman use the word "procedures" here, they mean what we would typically call "functions" today. Today, "procedural programming" basically means "imperative programming", and that is not the idiom they are teaching. (Where the exact term "procedure" is used nowadays — though it's less common now — it generally refers specifically to a function which does not return a usable value, which is called specifically for its side effects. SICP instead generally describes what we would now call "functional programming".)
> That is, you were explicitly asserting that the core material of SICP was concerned with "structure", "architecture", and "functions" in the sense of the core material of those courses
By "SICP" I clearly meant 6.001 and only 6.001, since that's the course titled as such ("SICP" stands for "Structure and Interpretation of Computer Programs").
I was not asserting that SICP was concerned with any term in the sense of the core material of any other course, which is why I didn't mention the other courses in that sentence. I was asserting that SICP was concerned with those concepts as they are commonly understood.
I wrote the comment knowing nothing of the content of the other courses, because nothing about the content of the other courses was relevant to the point I was making.
Please do not try to tell me what I meant by my own words.