Stanford CS240h, Functional Systems in Haskell

by rohshall • 14 years ago

81 40 14 years ago

Toshio• 14 years ago

At first I thought "Oh wow, video lectures a la Coursera, awesome", unfortunately these are just written materials.

I'm a little surprised at how little love FP gets at the Courseras, EDXs and Udacities of the world. The only thing that's going on at the moment is Martin Odersky's FP principles in Scala.

rohshall4• 14 years ago

http://dterei.blogspot.sg/2011/10/stanford-haskell-course.ht... He hints that it may become available online.

nightowl03d2• 14 years ago

That is funny, every time I see a course with a bunch of video lectures and no notes and reading list I move on. My strong preference for on-line learning is a reading list, ideally spread between no more than 3 or 4 books, a syllabus, and list of exercises.

If there are videos I listen to them while I am doing the homework associated with the video, but usually I get the homework done before the video finishes.

Disclaimer: I can probably get away with this because I already have a PhD and so I have a lot of practice in learning things

dlo• 14 years ago

It's really cool how you're able to complete homework while you're watching video. Can you get into more detail about how you're able to do this?

My roadblocks to doing this would be that I wouldn't be able to pay attention to what's going on while thinking about a homework problem, that some things need to turn over in my head before I understand it at the level needed to apply it, and that solutions often take a long time to type up, especially proofs and programming assignments.

pnathan2• 14 years ago

I am opposite, I almost never watch video materials or movies, or listen to podcasts.

I prefer learning from books. :-)

wonderzombie• 14 years ago

Books are nice! I used to feel the same way, in fact. But podcasts, et al, are nice for periods where you're mobile (commuting, walking the dog).

I was surprised to find how many more talks and whatnot I could get through just by loading them up on my phone and flipping them on when doing something else which required little attention. YMMV. :)

dmmalam2• 14 years ago

When I was at student at Imperial College, London, programming 1 was all taught in Haskell http://www.doc.ic.ac.uk/teaching/coursedetails/120.1

It seemed like a silly idea then, but in hindsight was a genius move. It normalised the class (prior knowledge in a real didn't matter), and taught programming from first principles. Picking up new languages after this was significancy easier.

rohshall4• 14 years ago

You are lucky. For first 8 years of my software career, I did not know anything other than C-based languages (except Lisp). Haskell made me realize what 'real' computer science is.

lclarkmichalek• 14 years ago

UCL does something similar. C is the first half of the first term, Haskell is the second half.

trhtrsh3• 14 years ago

How do you teach Haskell from first principles? Did you start with the lambda calculus and Core?

pav3l2• 14 years ago

I am not a computer scientist by training. Can someone experienced in Haskell convince me why I should take time to learn it? I do tons of technical/statistical computing (python, Matlab, R) and some web-based projects (database driven mostly). Having math background I can see how FP is elegant and sexy, but what are real practical advantages over OOP or Matlab-style programming?

lmm3• 14 years ago

Immutability means it's a lot easier to change your code safely. And the functional style encourages better separation of concerns, again making it easier to change something in one place. Strong typing is really good in a large codebase for making it harder for errors to propagate - if you make an error in a given function that changes the return type, you can immediately localise the problem to that function.

Writing the initial code is likely to be if anything slower in a functional language; the real advantage comes in maintenance.

(disclaimer: I don't actually know haskell, though I've used several functional languages and written functional-style code in several more)

ozataman3• 14 years ago

"Writing the initial code is likely to be if anything slower in a functional language; the real advantage comes in maintenance."

Definitely disagree with this. As with anything, with practice, you get very fast at writing Haskell code. the expressive/strong type system and type inference means you'll catch errors early while writing code at a higher/denser level than even today's popular dynamic languages, resulting in a net increase in programming speed (for me).

ozataman3• 14 years ago

That question has been answered 100s of times in various other HN threads, Reddit's haskell subtopic, stackoverflow, blogs, etc. There are many really good reasons - I would encourage you to make some simple use of Google to find out.

pav3l2• 14 years ago

Most arguments I've come across seem to be of the type "FP will make you a smarter programmer and better person, just try it and you'll see. Lot's of programmers are too dumb to get it though, so don't feel bad if you're one of them". I was hoping that someone here could provide some more concrete explanations of when Haskell & company should be used over imperative/OO designs. For example, the most watched Haskell repo on Github seems to be pandoc, an engine for converting text from one markup to another. What is it about functional programming that makes it better suited for this particular task then, say, Perl? Or is pandoc written in haskell for purely historical reasons? Maybe there is a better example.

rauljara• 14 years ago

I've tried a few times to learn Haskell, but always tend to lose steam. Last time I got as far as monads before petering out. So I am definitely not a great person to try explaining the practical benefits of Haskell programming, because I've never written anything more complicated than a moderately difficult project euler solution.

However, despite never actually reaching escape velocity with the language, I don't feel like I've wasted any time at all. It's made me a much better programmer. The restrictions that the language places on you (e.g., the inability to change a value once you declare it) forces you to really grapple with functional principles.

As a result, I am so much better at reasoning recursively, and figuring out how to compose functions, that I hardly believe it. As a ruby programmer, I thought I understood recursion. I thought I understood higher order functions. And I did. But at such a basic level that I had no idea how basic my understanding was. Haskell totally opened my eyes.

So, imho, even if you never use haskell, even if you never even fully learn it, the attempt will almost certainly make you a better programmer. Unless, of course, you've been already messing around with one of the other nearly pure functional programming languages out there.

dmmalam2• 14 years ago

completely agree. I've only written toy haskell programs, BUT it has heavily influences all my other code (js, c[++], java, ruby).

Ixiaus• 14 years ago

It took 3-4 years of learning Erlang and Scheme first before I could fully grok Haskell concepts. Monads aren't as bad as you think they are, read this if you haven't: http://ertes.de/articles/monads.html

Haskell's strengths: it's succinct, safe, feature-rich, and compiles to fast programs.

* Succinct: due to Haskell's strong focus on mathematical abstraction (I may be abusing that term here) it makes reasoning about programs easier on a general level - if you get the general case right then any potential problem that fits it will be solved by it. Succinctness also makes writing the code much faster (it's kind of like escape velocity with Emacs - takes a while to get a reasonable map down in your head, but once you do you're 5-10x more productive than you were before). * Safe: this one's obvious - Haskell's type system is brilliant in every way and paired with flymake for haskell can make writing robust code very straightforward. * Feature-rich: lots of libraries, native support for multi-processor/multi-core concurrency - I'm still waiting on something like OTP for Haskell though; Erlang takes the cake there simple because of OTP. * It's fast too; granted you have to be careful to not let non-strictness bite you in the ass, but that's generally very easy to profile and nail down if you can't.

I love Haskell, I use Erlang at my startup and I'm working on some big personal projects in Haskell.

batgaijin• 14 years ago

Okay here is an awesome description of monads: a function buddy!

Want to print out parts of a function? Want to log something? Don't add an argument to your function! Use a monad!

Basically if you have something orthogonal you want to do with a functions results, use a monad. You don't have to pass everything as an argument explicitly any more!

P.s. don't listen to this until a haskell demigod corrects me

tel• 14 years ago

I've been doing the same kind of work as you for a few years now while being somewhat proficient in Haskell.

The answer is, to me, that there's absolutely no reason to use Haskell for that kind of work.

It's rather conceivable that someone could build a statistical/scientific system that's driven by Haskell that would be useful, but fundamentally systems like Matlab/R/Python are far more suited for the exploratory analysis kind of programming that I used to do. YMMV but I wouldn't be surprised if it didn't.

That said, if I were implementing a statistical system I had designed and analyzed in Matlab/R/Python in a complex domain then I'd move to Haskell.

I think this issue would begin to evaporate if GHCi treated the IO monad differently. As it is GHCi is extremely valuable for exploring the structure of your own programs, but utterly terrible at exploring data. I find myself either constantly writing complex IO-unwrapping chains or deleting my state data when I build a new function and refresh the environment.

I'm building a complex system today that needs really well understood behavior, so I'm using Haskell. Whenever I want to see the data passing through it, though, I load up R.

rohshall4• 14 years ago

I went through the notes. They are concise, but not too concise. A nice tutorial for people who already know the basics. http://www.scs.stanford.edu/11au-cs240h/notes/

krat0sprakhar• 14 years ago

Is it just me or does anyone else always feels overwhelmed reading the project suggestions? I find the projects listed to be extremely challenging. Project suggestions - http://www.scs.stanford.edu/11au-cs240h/labs/project.html

dons2• 14 years ago

Some are easy, some are research level. They're all "open source"-style programming : i.e. add real features to real projects on a real time frame.

You could expect to apply to do these in the Summer of Code Haskell projects.

Challenging, yes, but not unrealistic for competent systems / language people.

anjc• 14 years ago

Eh, yes. Please tell me that, guessing from the course's name, this isn't a 2nd year course in some degree?

gwern• 14 years ago

I was amused at these suggestions:

> You could implement a 'bot that executes untrusted code along the lines of Lambdabot. Lambdabot was written before Haskell was typesafe, and as a result is fairly hairy code and very limited in functionality. Using type safety you ought to be able to achieve something much cleaner and simpler, and that provides far more functionality. > Implement some sort of end-user programmable web-site (like Wikipedia, but for code rather than for information). > Implement an online Haskell REPL environment such as Try Haskll. Using Safe Haskell and some of the recent support in GHC 7.3 for data declarations in GHCi you should be able to provide a far more powerful feature set then existing websites.

Try that, and you'll discover that much of the complexity in lambdabot/mueval/tryhaskell-mueval-fork is due to stuff that Safe Haskell won't help with! eg. good luck dealing with 'let x = x + 1 in x'

metaguri• 14 years ago

To my dismay CS240h was not offered again this year, probably because David Mazieres is teaching CS140 (Operating Systems) instead.

Stanford CS240h, Functional Systems in Haskell

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