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I never understood the appeal of this, or SICP, or Scheme in general. I learned much more about computer science reading algorithms and data structures textbook

I never understood the appeal of this, or SICP, or Scheme in general. I learned much more about computer science reading algorithms and data structures textbooks, especially Knuth. There's a reason MIT uses Python for its intro courses now, after all.

ska 6y ago
MIX/MMIX are close to how CPUs work physically. scheme is close to how computation works theoretically. The pedagogical approach that appeals to individuals tends to align with how they are most comfortable thinking about it.
- spekcular 6y ago
  Let me say something that may reveal my ignorance, but which I'm very happy to be corrected on: for the purpose of writing moderately-sized, everyday programs, I've never needed to understand how computation works theoretically (more abstractly than introductory algorithms and data structures). And that's not because I'm not comfortable with abstraction, or because I don't know how it works theoretically, I just haven't. Further, the obstacles I face when coding are mostly tightly coupled to the fact that I'm programming on physical hardware – again, nothing to do with the theory of computation. Even in a high-level language like Python, if you program the Sieve of Eratosthenes in a naive way without understanding what's going on under the hood with deleting an element from a list, you're going to have a bad time [0]. To caricature SICP-style instruction a bit, I'm imagining someone learning that recursion is useful (Scheme peeps seem to love it) without also being taught it generally has poor performance characteristics. Perhaps a better criticism is the mostly useless emphasis on immutable data structures. The example I like to bring up is how Haskell for a long time didn't have a readily-available hash table implementation for completely ideological reasons. No, hash maps are strictly worse, thank you. [0] https://stackoverflow.com/questions/3939660/sieve-of-eratosthenes-finding-primes-python https://stackoverflow.com/questions/3939660/sieve-of-eratost...
  - Jtsummers 6y ago
    > To caricature SICP-style instruction a bit, I'm imagining someone learning that recursion is useful (Scheme peeps seem to love it) without also being taught it generally has poor performance characteristics. SICP teaches that recursion can have bad performance and how to use it without blowing the stack or wasting time with unnecessary computations. Scheme, the language, requires tail call elimination so compilers will transform tail recursion into something as fast as a conventional loop.
    - spekcular 6y ago
      Yes, I agree, that is a caricature. More seriously, I think leaning on this language-specific feature in a book that's supposedly teaching "general programming 101," or whatever, is in bad taste. As it says: > One reason that the distinction between process and procedure may be confusing is that most implementations of common languages (including Ada, Pascal, and C) are designed in such a way that the interpretation of any recursive procedure consumes an amount of memory that grows with the number of procedure calls, even when the process described is, in principle, iterative. As a consequence, these languages can describe iterative processes only by resorting to special-purpose ``looping constructs'' such as do, repeat, until, for, and while. The implementation of Scheme we shall consider in chapter 5 does not share this defect. It will execute an iterative process in constant space, even if the iterative process is described by a recursive procedure. An implementation with this property is called tail-recursive. With a tail-recursive implementation, iteration can be expressed using the ordinary procedure call mechanism, so that special iteration constructs are useful only as syntactic sugar. This is an example of a point where an algorithms book is helpful + clarifying and SICP is really not. (fake quote: "Be conceptually sloppy and let Scheme take care of it, kid.") It has a few pages on orders of growth, but the coverage is not amazing.
      - chongli 6y ago
        I wouldn’t really call tail-call elimination a feature, language-specific or otherwise. Instead, I would describe the lack of it as a bug. If you examine what’s actually going on in compilers that lack tail call elimination, what you witness is the saving of registers to the stack whose values are provably never going to be used.
- bogomipz 6y ago
  >"MIX/MMIX are close to how CPUs work physically." What is MIX/MMIX? Is this something specific to the SICP book?
  - Jtsummers 6y ago
    From Knuth’s The Art of Computer Programming. MIX is the earlier version, MMIX is the more recent (though now 20 or so years old) version. They are descriptions of a computer architecture and machine instructions used to explore algorithms in his books. https://en.m.wikipedia.org/wiki/MMIX https://en.m.wikipedia.org/wiki/MMIX
  - astrange 6y ago
    Knuth's TAOCP was originally written in an imaginary 60s-style CISC assembly called MIX (with some oddities like being decimal) but newer editions are in a RISC style one called MMIX (which Knuth claims is more practical but really isn't.)
    - disgruntledphd2 6y ago
      Well, all I can say about that is that I read through the MMIX supplement and did a bunch of the exercises, and I know have enough knowledge to vaguely understand assembly. It hasn't been massively useful to me in my professional life (I'm a data scientist), but it definitely has helped me to gain a deeper appreciation of how computing works.
      - astrange 6y ago
        By practical I meant it's hard to implement in hardware. As far as I know it's easy to learn, having register windows is just kind of weird.
        disgruntledphd2 6y ago
        Ah OK. I guess that makes sense (especially as Knuth implemented its interpreter in C, as documented in MMIXware).
- vram22 6y ago
  Both understandings are needed for best results.
deleted 6y ago
[deleted]
flatline 6y ago
SICP introduced a lot of fundamental concepts in CS to me as a junior, self-taught developer. Building everything up using immutable functions and then introducing mutable state was revelatory and still influences my design decisions 15+ years on. Scheme was somewhat beside the point.
qbasic_forever 6y ago
SICP for me was the missing link between learning syntax and code to designing actual programs that solve real problems. It made me step back and look at a problem not as something that just needs a layer of code thrown at it, but as a task to complete, with requirements, constraints, etc. to consider before a single line of code is even written.
wjossey 6y ago
While I have friends (and many colleagues) who graduated from MIT CS and are very competent engineers, I don't think MIT is the shining beacon of the best SE/CS graduates. Their program is certainly very good, but if someone asked me (for CS/SE specifically) about going to MIT or NU, I'd point them to NU. For almost everything else, it would, of course, be MIT.
- aiisjustanif 6y ago
  What university is NU?
  - wjossey 6y ago
    Northeastern University, which is where the roots of HTDP can be found.
    - aiisjustanif 6y ago
      Ah, thank you. I was thinking of Northwestern. To the point of comment you replied too. I do believe there is value in what can be more understood between learning via HTDP vs an easy to understand language, Data Structures, and Algorithms. From stand point of teaching CS to beginners maybe MIT is going for breath and Northeastern is going more for depth. Then again what do I know, I didn’t go to university remotely in that realm of prestige.
- webmobdev 6y ago
  What about Carnegie Mellon or Berkley?
TeMPOraL 6y ago
> There's a reason MIT uses Python for its intro courses now, after all. Yes, and IIRC, that reasons were, roughly: a) Python is more popular, b) Python has better robotics libraries, which is what kids coming to MIT care about these days. Notably, I don't recall the reasons they given having anything to do with giving students a good fundamental understanding.
- spekcular 6y ago
  But this is exactly my point. I think it's essentially a myth that Scheme/SICP are somehow more well-suited to providing a "good fundamental understanding." And Python is, as you point out, more practical and accessible.
- ralphc 6y ago
  Here is Gerald Sussman, creator of SICP and the course, explaining exactly what happened with the switch - https://www.youtube.com/watch?v=cblhgNUoX9M&t=3578s https://www.youtube.com/watch?v=cblhgNUoX9M&t=3578s

ska 6y ago

MIX/MMIX are close to how CPUs work physically. scheme is close to how computation works theoretically. The pedagogical approach that appeals to individuals tends to align with how they are most comfortable thinking about it.

spekcular 6y ago
Let me say something that may reveal my ignorance, but which I'm very happy to be corrected on: for the purpose of writing moderately-sized, everyday programs, I've never needed to understand how computation works theoretically (more abstractly than introductory algorithms and data structures). And that's not because I'm not comfortable with abstraction, or because I don't know how it works theoretically, I just haven't. Further, the obstacles I face when coding are mostly tightly coupled to the fact that I'm programming on physical hardware – again, nothing to do with the theory of computation. Even in a high-level language like Python, if you program the Sieve of Eratosthenes in a naive way without understanding what's going on under the hood with deleting an element from a list, you're going to have a bad time [0]. To caricature SICP-style instruction a bit, I'm imagining someone learning that recursion is useful (Scheme peeps seem to love it) without also being taught it generally has poor performance characteristics. Perhaps a better criticism is the mostly useless emphasis on immutable data structures. The example I like to bring up is how Haskell for a long time didn't have a readily-available hash table implementation for completely ideological reasons. No, hash maps are strictly worse, thank you. [0] https://stackoverflow.com/questions/3939660/sieve-of-eratosthenes-finding-primes-python https://stackoverflow.com/questions/3939660/sieve-of-eratost...
- Jtsummers 6y ago
  > To caricature SICP-style instruction a bit, I'm imagining someone learning that recursion is useful (Scheme peeps seem to love it) without also being taught it generally has poor performance characteristics. SICP teaches that recursion can have bad performance and how to use it without blowing the stack or wasting time with unnecessary computations. Scheme, the language, requires tail call elimination so compilers will transform tail recursion into something as fast as a conventional loop.
  - spekcular 6y ago
    Yes, I agree, that is a caricature. More seriously, I think leaning on this language-specific feature in a book that's supposedly teaching "general programming 101," or whatever, is in bad taste. As it says: > One reason that the distinction between process and procedure may be confusing is that most implementations of common languages (including Ada, Pascal, and C) are designed in such a way that the interpretation of any recursive procedure consumes an amount of memory that grows with the number of procedure calls, even when the process described is, in principle, iterative. As a consequence, these languages can describe iterative processes only by resorting to special-purpose ``looping constructs'' such as do, repeat, until, for, and while. The implementation of Scheme we shall consider in chapter 5 does not share this defect. It will execute an iterative process in constant space, even if the iterative process is described by a recursive procedure. An implementation with this property is called tail-recursive. With a tail-recursive implementation, iteration can be expressed using the ordinary procedure call mechanism, so that special iteration constructs are useful only as syntactic sugar. This is an example of a point where an algorithms book is helpful + clarifying and SICP is really not. (fake quote: "Be conceptually sloppy and let Scheme take care of it, kid.") It has a few pages on orders of growth, but the coverage is not amazing.
    - chongli 6y ago
      I wouldn’t really call tail-call elimination a feature, language-specific or otherwise. Instead, I would describe the lack of it as a bug. If you examine what’s actually going on in compilers that lack tail call elimination, what you witness is the saving of registers to the stack whose values are provably never going to be used.
bogomipz 6y ago
>"MIX/MMIX are close to how CPUs work physically." What is MIX/MMIX? Is this something specific to the SICP book?
- Jtsummers 6y ago
  From Knuth’s The Art of Computer Programming. MIX is the earlier version, MMIX is the more recent (though now 20 or so years old) version. They are descriptions of a computer architecture and machine instructions used to explore algorithms in his books. https://en.m.wikipedia.org/wiki/MMIX https://en.m.wikipedia.org/wiki/MMIX
- astrange 6y ago
  Knuth's TAOCP was originally written in an imaginary 60s-style CISC assembly called MIX (with some oddities like being decimal) but newer editions are in a RISC style one called MMIX (which Knuth claims is more practical but really isn't.)
  - disgruntledphd2 6y ago
    Well, all I can say about that is that I read through the MMIX supplement and did a bunch of the exercises, and I know have enough knowledge to vaguely understand assembly. It hasn't been massively useful to me in my professional life (I'm a data scientist), but it definitely has helped me to gain a deeper appreciation of how computing works.
    - astrange 6y ago
      By practical I meant it's hard to implement in hardware. As far as I know it's easy to learn, having register windows is just kind of weird.
      - disgruntledphd2 6y ago
        Ah OK. I guess that makes sense (especially as Knuth implemented its interpreter in C, as documented in MMIXware).
vram22 6y ago
Both understandings are needed for best results.

deleted 6y ago

[deleted]

flatline 6y ago

SICP introduced a lot of fundamental concepts in CS to me as a junior, self-taught developer. Building everything up using immutable functions and then introducing mutable state was revelatory and still influences my design decisions 15+ years on. Scheme was somewhat beside the point.

qbasic_forever 6y ago

SICP for me was the missing link between learning syntax and code to designing actual programs that solve real problems. It made me step back and look at a problem not as something that just needs a layer of code thrown at it, but as a task to complete, with requirements, constraints, etc. to consider before a single line of code is even written.

wjossey 6y ago

While I have friends (and many colleagues) who graduated from MIT CS and are very competent engineers, I don't think MIT is the shining beacon of the best SE/CS graduates. Their program is certainly very good, but if someone asked me (for CS/SE specifically) about going to MIT or NU, I'd point them to NU. For almost everything else, it would, of course, be MIT.

aiisjustanif 6y ago
What university is NU?
- wjossey 6y ago
  Northeastern University, which is where the roots of HTDP can be found.
  - aiisjustanif 6y ago
    Ah, thank you. I was thinking of Northwestern. To the point of comment you replied too. I do believe there is value in what can be more understood between learning via HTDP vs an easy to understand language, Data Structures, and Algorithms. From stand point of teaching CS to beginners maybe MIT is going for breath and Northeastern is going more for depth. Then again what do I know, I didn’t go to university remotely in that realm of prestige.
webmobdev 6y ago
What about Carnegie Mellon or Berkley?

TeMPOraL 6y ago

> There's a reason MIT uses Python for its intro courses now, after all. Yes, and IIRC, that reasons were, roughly: a) Python is more popular, b) Python has better robotics libraries, which is what kids coming to MIT care about these days. Notably, I don't recall the reasons they given having anything to do with giving students a good fundamental understanding.

spekcular 6y ago
But this is exactly my point. I think it's essentially a myth that Scheme/SICP are somehow more well-suited to providing a "good fundamental understanding." And Python is, as you point out, more practical and accessible.
ralphc 6y ago
Here is Gerald Sussman, creator of SICP and the course, explaining exactly what happened with the switch - https://www.youtube.com/watch?v=cblhgNUoX9M&t=3578s https://www.youtube.com/watch?v=cblhgNUoX9M&t=3578s