Why MIT switched from Scheme to Python (2009) • Hacker News Board

Re: Why MIT switched from Scheme to Python (2009)

#131

Post by Koshkin » Fri, Jul 25, 2025, 9:30 PM UTC

raverbashing wrote: post #29

MontyCarloHall wrote: post #14

Isn't this just part of the broader trend of CS departments switching away from teaching computer science to teaching computer engineering, which in turn is part of the more general trend of colleges becoming more vocational? LISP dialects like Scheme are excellent for teaching pure computer science because they are the closest thing to executing lambda calculus expressions. Whereas Python is excellent for teaching a…

Lambda Calculus is one of those things that look good on paper as a theory construct but in practice it's not a great abstraction. And honestly you could go your whole career without touching it, maybe only for the naming of an anonymous function. Boolean logic, graphs, FSMs, set theory, mathematical proofs, pretty much all user here or there. Lambda calculus? Unless you're one of those Haskell fans, meh.

> Haskell

https://book.realworldhaskell.org/

Re: Why MIT switched from Scheme to Python (2009)

#132

Post by anthk » Fri, Jul 25, 2025, 9:31 PM UTC

trothamel wrote: post #84

acuozzo wrote: post #49

Earlier quoted context omitted.

Knowing your way around the ecosystem of one programming language does not build up the intuition necessary for identifying O(n²) (or worse!) algorithms and choosing/writing O(log(n)) (or better!) ones instead. Computer Science has little to do with science, but what it teaches you is certainly closer to science than just building a huge mental index for a bunch of work done by other people. There's certainly value i…

> Knowing your way around the ecosystem of one programming language does not build up the intuition necessary for identifying O(n²) (or worse!) algorithms and choosing/writing O(log(n)) (or better!) ones instead. I'll disagree with this, at least in terms of Scheme versus Python. Python is visually close enough to other languages that the skills you develop to quickly see O(n²) algorithms easily transfer to many othe…

Scheme has (trace), at least most interpreters (and his cousing Common Lisp) have some tracing and pretty-printing features. Far more powerful than anything Python could offer.

Oh, and of course it has functions like sdraw or draw-cons-tree when you can print the contents of a list in seconds as an ASCII-ART chart:

https://www.t3x.org/s9fes/draw-tree.scm.html

The file it's in the public domain.

Try that with Python.

Re: Why MIT switched from Scheme to Python (2009)

#133

Post by zahlman » Fri, Jul 25, 2025, 9:32 PM UTC

MontyCarloHall wrote: post #14

Isn't this just part of the broader trend of CS departments switching away from teaching computer science to teaching computer engineering, which in turn is part of the more general trend of colleges becoming more vocational? LISP dialects like Scheme are excellent for teaching pure computer science because they are the closest thing to executing lambda calculus expressions. Whereas Python is excellent for teaching a…

> Whereas Python is excellent for teaching applied computer engineering, because it's essentially executable pseudocode for imperative languages

Python offers quite good multi-paradigm support and could absolutely be used to explore many key concepts from SICP (granted, nothing is as meta-programmable as the Lisp family, since AST manipulation in other languages requires additional steps to actually obtain an AST). In particular, since Python's object model includes functions, higher-order functions are possible (and indeed, `map` is a builtin, and `reduce` is in the standard library after previous demotion from builtin status). Nowadays of course it's fashionable to litter the code with manifest type hints, which are a distraction to that sort of pedagogy. However, they are still entirely optional, have zero-to-generally-irrelevant effect at runtime, and can simply be disregarded.

Re: Why MIT switched from Scheme to Python (2009)

#134

Post by warbaker » Fri, Jul 25, 2025, 9:32 PM UTC

16 years later, I'm still disappointed about this decision. The justification for it is just awful: "6.001 had been conceived to teach engineers how to take small parts that they understood entirely and use simple techniques to compose them into larger things that do what you want. But programming now isn’t so much like that, said Sussman. Nowadays you muck around with incomprehensible or nonexistent man pages for software you don’t know who wrote."

This is just false. Engineering is still about taking small parts you understand entirely and using simple techniques to compose them into larger things you want. Sussman's justification is an abject surrender to shitty complexity. Engineers need to develop a taste for simplicity and elegance, especially at the beginning of their education.

Incidentally, an overlooked advantage of teaching in Scheme is that it levels the playing field, as pre-undergrad programming classes almost never use functional languages.

Re: Why MIT switched from Scheme to Python (2009)

#135

Post by unethical_ban » Fri, Jul 25, 2025, 9:36 PM UTC

NewsaHackO wrote: post #120

unethical_ban wrote: post #73

Earlier quoted context omitted.

Do you agree or disagree that Python is more readable/closer to pseudocode than say Java or C++? Less syntactic sugar, no need to define namespaces/classes, more intuitive for declarations, etc.

Would you consider essentially dry water to be semantically correct phrase?

I understood the meaning of their phrase and explained it. You assert that the original phrase is incomprehensible and meaningless. We see things differently.

Re: Why MIT switched from Scheme to Python (2009)

#136

Post by losvedir » Fri, Jul 25, 2025, 9:41 PM UTC

keithwinstein wrote: post #75

This story has been reposted many times, and I think GJS's remarks (as recorded by Andy Wingo) are super-interesting as always, but this is really not a great account of "why MIT switched from Scheme to Python." Source: I worked with GJS (I also know Alexey and have met Andy Wingo), and I took 6.001, my current research still has us referring to SICP on a regular basis, and in 2006 Kaijen Hsiao and I were the TAs for…

Thanks for this history, very interesting! I guess I can see the reasoning there, but as an Econ major who took 6.001 for fun, it makes me a little sad. That class was mindbending and so interesting.

Re: Why MIT switched from Scheme to Python (2009)

#137

Post by pledess » Fri, Jul 25, 2025, 9:42 PM UTC

warbaker wrote: post #134

16 years later, I'm still disappointed about this decision. The justification for it is just awful: "6.001 had been conceived to teach engineers how to take small parts that they understood entirely and use simple techniques to compose them into larger things that do what you want. But programming now isn’t so much like that, said Sussman. Nowadays you muck around with incomprehensible or nonexistent man pages for so…

His top students were capable of entirely understanding Scheme within a day or so (but not capable of entirely understanding all of Python and all of PyPI). He wanted students to be even better than that. He wanted them to lead productive and resilient collaborations even when they didn't or couldn't entirely understand the small parts.

Re: Why MIT switched from Scheme to Python (2009)

#138

Post by unixhero » Fri, Jul 25, 2025, 9:43 PM UTC

I hated learning Scheme on their free open courseware. Yet I loved that it was free :)

Re: Why MIT switched from Scheme to Python (2009)

#139

Post by zahlman » Fri, Jul 25, 2025, 9:45 PM UTC

cs_throwaway wrote: post #87

mrexroad wrote: post #8

Ga Tech used to teach Scheme as an intro to CS course. I vividly remember sitting in lecture and being struck w/ the implications of functional programming as the professor said you could pass functions into functions and modify them. It was as formative of a moment as my 2nd Grade teacher showing us a really complex looking (at the time) rainbow flower in LOGO (she had one of few color Mac classic), and showing us i…

It is possible that this doesn't work anymore. I distinctly recall the following episode when I last taught intro CS in Scheme: I revealed first-class functions. After lecture, the brightest kid in class came up to me and said something to the effect of, "What's the big deal? You can do this in Python."

That should be the beginning of the formative experience for that kid rather than the end. Yes, you can. How often do you? What are you missing by not thinking about problems in that way more often? What idioms could be unlocked that way? (How many Python programmers out there are aping wholly unnecessary "design patterns" created for C++ or Java? Or rather: shouldn't a design pattern be about the design rather than the implementation? What is a design, in the pure abstract, really?)

Re: Why MIT switched from Scheme to Python (2009)

#140

Post by zahlman » Fri, Jul 25, 2025, 9:47 PM UTC

warbaker wrote: post #134

16 years later, I'm still disappointed about this decision. The justification for it is just awful: "6.001 had been conceived to teach engineers how to take small parts that they understood entirely and use simple techniques to compose them into larger things that do what you want. But programming now isn’t so much like that, said Sussman. Nowadays you muck around with incomprehensible or nonexistent man pages for so…

> Engineering is still about taking small parts you understand entirely and using simple techniques to compose them into larger things you want.

Engineering fundamentally is still about that. But what people seem to do with computers nowadays mainly involves composing already-large parts that they absolutely do not understand. Often with disastrous results.