7 ms·

Some advice on teaching FP

44 points by tianyicui 15y ago

assfucker4000 15y ago
There are several reasons that these posts are annoying. If you read HN and are a programmer, then what do you have to gain from this? If you read HN and aren't, one could ask a similar question. The real annoyance, however, is that this (and the recent rash of posts about Stanford's "innovative" CS curriculum) make a whole lot of sense to technical people. Do you ever think about how, as technical people, the way that you think is different from those around you? Certainly. And wouldn't it be great if they saw the world as you do? Certainy. So, teach them how to do so in a course designed for YOU. That'll teach 'em. Just like the literature courses you took spoke to you so clearly. Oh, wait, they did? Then you're one of the people at the top that don't need a curriculum that is carefully designed to change the way that you think. You just need to be presented with new and interesting ideas and you'll run with them. So, Stanford and CMU, stop pretending that you're changing minds; admit that you're just enhancing them. Those of us who don't have 1600 SAT students to hide behind have been doing this for years...and don't need "advice on teaching FP."
rntz 15y ago
I'm a TA (one of four) for the course Harper is talking about in this post. As they say on reddit, ask me anything. I do not guarantee I'll answer. I'll check back in in the morning.
- toadstone 15y ago
  I remember it being a rare event when 212 created a FP enthusiast. Are the students in the new course liking it or just enduring it?
  - rntz 15y ago
    That's hard for me to know because, as a TA, I mostly get to see students when they're confused or frustrated, up against a deadline. The fact that almost all our students are also enrolled in spring 251 with Luis von Ahn, and therefore incredibly overworked, doesn't help. However, a reasonable proportion of students seem interested, and a handful are overtly enthusiastic about the course. If I had to guess I'd say it won't be an order-of-magnitude improvement over 212, but it will be significant one, if only because it will reach more students earlier in their undergraduate careers. However, only time will tell. As for 212's reputation, you and I must run in different circles; I know plenty of FP enthusiasts who got their first taste in 212. I suspect a strong selection bias is at work here.
- szany 15y ago
  Thoughts on SML vs. Haskell?
  - rntz 15y ago
    In brief: I prefer Haskell, but I think it has its flaws, and I understand why we're not using it as a teaching language. In long: Haskell has much better concrete syntax, better library and tool support, a more active community, and is subjectively nicer to program in. Haskell is lazy, SML eager. Haskell catches a lot of flack about this from SML fans. I think the typical arguments against laziness (makes it hard to reason about space usage; just a special-case of eagerness) are not false but overblown (it's harder but not that hard once you get used to it; and yes, you can simulate laziness in an eager language using thunks etc, but that's a Turing tarpit argument). However, in the end I'm not sure laziness is worth it. Haskell is pure and SML is not. I don't mind the impurity of SML (or any other language), but I think Haskell's purity has some nice side-benefits for a high-level FP language (eg. allows more compiler optimizations). I'm also grateful to it for being the main reason Haskell has support for monads, which I think are a powerful unifying idea well worth their weight even if you don't need them to encapsulate I/O & side-effects. The big difference is, of course, their module systems. Everything Harper says about Haskell in this regard (https://existentialtype.wordpress.com/2011/04/16/modules-matter-most/ https://existentialtype.wordpress.com/2011/04/16/modules-mat...) is true, but I don't think it's as big of an issue as he makes out. Typeclasses give you 90% of what you want, in a much more concise package. I've perhaps wanted ML-style modules & functors once or twice when writing Haskell, and I wish I had typeclasses all the time when writing SML. I could say more on this topic, but this response is already overlong.
- cwzwarich 15y ago
  Has Harper actually done any real programming of significance? I am an "industry programmer" who has a pretty strong theoretical bent (have a math degree rather than CS, have read most of Harper's papers on the type theory and semantics of module systems), but when I read his blog posts I get the feeling that when it comes to programming he doesn't really know what's up.
  - rntz 15y ago
    I dunno, I just TA for the guy. I suspect it depends on what you mean by "real programming of significance". I can tell you that Harper is really damn smart. I'd be truly surprised if he was bad at programming. But his actual experience, I don't know. He hasn't written any code for the course itself, but that's not really his role.
- babeKnuth 15y ago
  Oddly enough, I'll be TAing an identical class this summer. Any quick tips or advice? (I'll probably also send you a message later as well). Thanks.
- babeKnuth 15y ago
  What concept(s) did the students find hardest to grasp? What areas do you think more time should be spent on when teaching it? Thnx in advance.
onan_barbarian 15y ago
Bob is an incredibly smart and accomplished guy, and I imagine the students will get a lot from the course. That being said the tone of triumphalism and the suggestion that a whole bunch of tough problems in CS (parallelism, program verification of real systems) are about to be solved by the majesty of strongly-typed functional languages is awfully familiar from the way Bob was talking about 15-20 years ago. We certainly have seen many interesting research papers, type systems and compilers since then, but I'm not sure whether much progress has been made on anything more visible to the much-maligned 'working programmer'.
- _delirium 15y ago
  The more worrying thing from a pedagogical point of view is his claim that a bunch of problems that programmers outside academia regularly deal with are non-problems and don't need to be taught, because they're cruft that is on the verge of obsolescence. He had better be right, or he'll be helping to produce a cohort of students who don't know a lot of stuff they might find themselves needing to know! (Of course, I realize that Harper doesn't control the entire CMU curriculum, so it's quite possible that despite his views, CMU students will end up studying the "not worth studying" versions of parallelism/architecture/etc. problems and solutions in other courses.)
  - parenthesis 15y ago
    This is a first year course. I think the idea is to teach students a `right way' before sullying their minds with real world `wrong ways' and more practical concerns.
    - _delirium 15y ago
      That does require that the right way is right! Harper is quite intelligent, but I think his particular views on what constitutes the "right way" to do programming are decidedly minority ones, even among academic computer scientists. Some have relatively large minority support (his views on FP are common among PLs researchers), but others get more and more into small-minority territory. He essentially believes that ML does things right or close to right, while every other language is horribly broken (Haskell somewhat less broken than others, but still fatally flawed), which isn't a very common view. His views on dynamic languages, OO, automata theory, and anything else that isn't FP are also quite partisan and often not widely held. I'm a bit uncomfortable with a partisan approach to an intro-level course, that presents the "correct" way to do things according to one particular professor's views. That sort of partisan-indoctrination-as-curriculum is something people rightfully complain about in some humanities departments. I don't think we'd do well in CS to follow their lead, with different universities teaching different partisan versions of CS 101, trying to convince their students that the "ML way" or the "Haskell way" or the "OO way" or the "Lisp way" is the one and only right way to do programming.
babeKnuth 15y ago
"One beautiful feature of the language-based approach is that we start with a very familiar model of computation, the evaluation of polynomials over the reals. It’s very familiar for all students, and I think they find it very satisfying precisely because it has a direct computational flavor." Don't know how true this is at other universities, but this doesn't sound like my experience at all. :)

44 points by tianyicui 15y ago

There are several reasons that these posts are annoying. If you read HN and are a programmer, then what do you have to gain from this? If you read HN and aren't, one could ask a similar question. The real annoyance, however, is that this (and the recent rash of posts about Stanford's "innovative" CS curriculum) make a whole lot of sense to technical people. Do you ever think about how, as technical people, the way that you think is different from those around you? Certainly. And wouldn't it be great if they saw the world as you do? Certainy. So, teach them how to do so in a course designed for YOU. That'll teach 'em. Just like the literature courses you took spoke to you so clearly. Oh, wait, they did? Then you're one of the people at the top that don't need a curriculum that is carefully designed to change the way that you think. You just need to be presented with new and interesting ideas and you'll run with them. So, Stanford and CMU, stop pretending that you're changing minds; admit that you're just enhancing them. Those of us who don't have 1600 SAT students to hide behind have been doing this for years...and don't need "advice on teaching FP."

rntz 15y ago

I'm a TA (one of four) for the course Harper is talking about in this post. As they say on reddit, ask me anything. I do not guarantee I'll answer. I'll check back in in the morning.

toadstone 15y ago
I remember it being a rare event when 212 created a FP enthusiast. Are the students in the new course liking it or just enduring it?
- rntz 15y ago
  That's hard for me to know because, as a TA, I mostly get to see students when they're confused or frustrated, up against a deadline. The fact that almost all our students are also enrolled in spring 251 with Luis von Ahn, and therefore incredibly overworked, doesn't help. However, a reasonable proportion of students seem interested, and a handful are overtly enthusiastic about the course. If I had to guess I'd say it won't be an order-of-magnitude improvement over 212, but it will be significant one, if only because it will reach more students earlier in their undergraduate careers. However, only time will tell. As for 212's reputation, you and I must run in different circles; I know plenty of FP enthusiasts who got their first taste in 212. I suspect a strong selection bias is at work here.
szany 15y ago
Thoughts on SML vs. Haskell?
- rntz 15y ago
  In brief: I prefer Haskell, but I think it has its flaws, and I understand why we're not using it as a teaching language. In long: Haskell has much better concrete syntax, better library and tool support, a more active community, and is subjectively nicer to program in. Haskell is lazy, SML eager. Haskell catches a lot of flack about this from SML fans. I think the typical arguments against laziness (makes it hard to reason about space usage; just a special-case of eagerness) are not false but overblown (it's harder but not that hard once you get used to it; and yes, you can simulate laziness in an eager language using thunks etc, but that's a Turing tarpit argument). However, in the end I'm not sure laziness is worth it. Haskell is pure and SML is not. I don't mind the impurity of SML (or any other language), but I think Haskell's purity has some nice side-benefits for a high-level FP language (eg. allows more compiler optimizations). I'm also grateful to it for being the main reason Haskell has support for monads, which I think are a powerful unifying idea well worth their weight even if you don't need them to encapsulate I/O & side-effects. The big difference is, of course, their module systems. Everything Harper says about Haskell in this regard (https://existentialtype.wordpress.com/2011/04/16/modules-matter-most/ https://existentialtype.wordpress.com/2011/04/16/modules-mat...) is true, but I don't think it's as big of an issue as he makes out. Typeclasses give you 90% of what you want, in a much more concise package. I've perhaps wanted ML-style modules & functors once or twice when writing Haskell, and I wish I had typeclasses all the time when writing SML. I could say more on this topic, but this response is already overlong.
cwzwarich 15y ago
Has Harper actually done any real programming of significance? I am an "industry programmer" who has a pretty strong theoretical bent (have a math degree rather than CS, have read most of Harper's papers on the type theory and semantics of module systems), but when I read his blog posts I get the feeling that when it comes to programming he doesn't really know what's up.
- rntz 15y ago
  I dunno, I just TA for the guy. I suspect it depends on what you mean by "real programming of significance". I can tell you that Harper is really damn smart. I'd be truly surprised if he was bad at programming. But his actual experience, I don't know. He hasn't written any code for the course itself, but that's not really his role.
babeKnuth 15y ago
Oddly enough, I'll be TAing an identical class this summer. Any quick tips or advice? (I'll probably also send you a message later as well). Thanks.
babeKnuth 15y ago
What concept(s) did the students find hardest to grasp? What areas do you think more time should be spent on when teaching it? Thnx in advance.

onan_barbarian 15y ago

Bob is an incredibly smart and accomplished guy, and I imagine the students will get a lot from the course. That being said the tone of triumphalism and the suggestion that a whole bunch of tough problems in CS (parallelism, program verification of real systems) are about to be solved by the majesty of strongly-typed functional languages is awfully familiar from the way Bob was talking about 15-20 years ago. We certainly have seen many interesting research papers, type systems and compilers since then, but I'm not sure whether much progress has been made on anything more visible to the much-maligned 'working programmer'.

_delirium 15y ago
The more worrying thing from a pedagogical point of view is his claim that a bunch of problems that programmers outside academia regularly deal with are non-problems and don't need to be taught, because they're cruft that is on the verge of obsolescence. He had better be right, or he'll be helping to produce a cohort of students who don't know a lot of stuff they might find themselves needing to know! (Of course, I realize that Harper doesn't control the entire CMU curriculum, so it's quite possible that despite his views, CMU students will end up studying the "not worth studying" versions of parallelism/architecture/etc. problems and solutions in other courses.)
- parenthesis 15y ago
  This is a first year course. I think the idea is to teach students a `right way' before sullying their minds with real world `wrong ways' and more practical concerns.
  - _delirium 15y ago
    That does require that the right way is right! Harper is quite intelligent, but I think his particular views on what constitutes the "right way" to do programming are decidedly minority ones, even among academic computer scientists. Some have relatively large minority support (his views on FP are common among PLs researchers), but others get more and more into small-minority territory. He essentially believes that ML does things right or close to right, while every other language is horribly broken (Haskell somewhat less broken than others, but still fatally flawed), which isn't a very common view. His views on dynamic languages, OO, automata theory, and anything else that isn't FP are also quite partisan and often not widely held. I'm a bit uncomfortable with a partisan approach to an intro-level course, that presents the "correct" way to do things according to one particular professor's views. That sort of partisan-indoctrination-as-curriculum is something people rightfully complain about in some humanities departments. I don't think we'd do well in CS to follow their lead, with different universities teaching different partisan versions of CS 101, trying to convince their students that the "ML way" or the "Haskell way" or the "OO way" or the "Lisp way" is the one and only right way to do programming.

babeKnuth 15y ago

"One beautiful feature of the language-based approach is that we start with a very familiar model of computation, the evaluation of polynomials over the reals. It’s very familiar for all students, and I think they find it very satisfying precisely because it has a direct computational flavor." Don't know how true this is at other universities, but this doesn't sound like my experience at all. :)