Amir Chaudhry

thoughts, comments & general ramblings

Review of the OCaml FPDays tutorial

Last Thursday a bunch of us from the OCaml Labs team gave an OCaml tutorial at the FPDays conference (an event for people interested in Functional Programming). Jeremy and I led the session with Leo, David and Philippe helping everyone progress and dealing with questions.

It turned out to be by far the most popular session at the conference with over 20 people all wanting to get to grips with OCaml! An excellent turnout and a great indicator of the interest that’s out there, especially when you offer a hands-on session to people. This shouldn’t be a surprise as we’ve had good attendance for the general OCaml meetups I’ve run and also the compiler hacking sessions, which Jeremy and Leo have been building up (do sign up if you’re interested in either of those!). We had a nice surprise for attendees, which were uncorrected proof copies of Real World OCaml and luckily, we had just enough to go around.

For the tutorial itself, Jeremy put together a nice sequence of exercises and a skeleton repo (with helpful comments in the code) so that people could dive in quickly. The event was set up to be really informal and the rough plan was as following:

  1. Installation/Intro - We checked that people had been able to follow the installation instructions, which we’d sent them in advance. We also handed out copies of the book and made sure folks were comfortable with OPAM.

  2. Hello world - A light intro to get people familiar with the OCaml syntax and installing packages with OPAM. This would also help people to get familiar with the toolchain, workflow and compilation.

  3. Monty Hall browser game - Using js_of_ocaml, we wanted people to create and run the Monty Hall problem in their browser. This would give people a taste of some real world interaction by having to deal with the DOM and interfaces. If folks did well, they could add code to keep logs of the game results.

  4. Client-server game - The previous game was all in the browser (so could be examined by players) so here the task was to split it into a client and server, ensuring the two stay in sync. This would demonstrate the re-usability of the OCaml code already written and give people a feel for client server interactions. If people wanted to do more, they could use ctypes and get better random numbers.

We did manage to stick to the overall scheme as above and we think this is a great base from which to improve future tutorials. It has the really nice benefit of having visual, interactive elements and the ability to run things both in the browser as well as on the server is a great way to show the versatility of OCaml. js_of_ocaml is quite a mature tool and so it’s no surprise that it’s also used by companies such as Facebook (see the recent CUFP talk by Julien Verlaguet - skip to 19:00).

We learned a lot from running this session so we’ve captured the good, the bad and the ugly below. This is useful for anyone who’d like to run an OCaml tutorial in the future and also for us to be aware of the next time we do this. I’ve incorporated the feedback from the attendees as well as our own thoughts.

Heads down and hands on

Things we learnt

The Good

  • Most people really did follow the install instructions beforehand. This made things so much easier on the day as we didn’t have to worry about compile times and people getting bored. A few people had even got in touch with me the night before to sort out installation problems.

  • Many folks from OCaml Labs also came over to help people, which meant no-one was waiting longer than around 10 seconds before getting help.

  • We had a good plan of the things we wanted to cover but we were happy to be flexible and made it clear the aim was to get right into it. Several folks told us that they really appreciated this loose (as opposed to rigid) structure.

  • We didn’t spend any time lecturing the room but instead got people right into the code. Having enough of a skeleton to get something interesting working was a big plus in this regard. People did progress from the early examples to the later ones fairly well.

  • We had a VM with the correct set up that we could log people into if they were having trouble locally. Two people made use of this.

  • Of course, It was great to have early proofs of the book and these were well-received.

RWO books galore!

The Bad

  • In our excitement to get right into the exercises, we didn’t really give an overview of OCaml and its benefits. A few minutes at the beginning would be enough and it’s important so that people can leave with a few sound-bites.

  • Not everyone received my email about installation, and certainly not the late arrivals. This meant some pain getting things downloaded and running especially due to the wifi (see ‘Ugly’ below).

  • A few of the people who had installed, didn’t complete the instructions fully but didn’t realise this until the morning of the session. There was a good suggestion about having some kind of test to run that would check everything, so you’d know if there was something missing.

  • We really should have had a cut-off where we told people to use VMs instead of fixing installation issues and 10-15 minutes would have been enough. This would have been especially useful for the late-comers.

  • We didn’t really keep a record of the problems folks were having so we can’t now go back and fix underlying issues. To be fair, this would have been a little awkward to do ad-hoc but in hindsight, it’s a good thing to plan for.

The Ugly

  • The only ugly part was the wifi. It turned out that the room itself was a bit of a dead-spot and that wasn’t helped by 30ish devices trying to connect to one access point! Having everyone grab packages at the same time in the morning probably didn’t help. It was especially tricky as all our mitigation plans seemed to revolve around at least having local connectivity. In any case, this problem only lasted for the morning session and was a little better by the afternoon. I’d definitely recommend a backup plan in the case of complete wifi failure next time! One such plan that Leo got started on was to put the repository and other information onto a flash drive that could be shared with people. We didn’t need this in the end but it’ll be useful to have something like this prepared for next time. If anyone fancies donating a bunch of flash drives, I’ll happily receive them!

Overall, it was a great session and everyone left happy, having completed most of the tutorial (and with a book!). A few even continued at home afterwards and got in touch to let us know that they got everything working. It was a great session and thanks to Mark, Jacqui and the rest of the FPDays crew for a great conference!

RWO Book giveaway

(Thanks to Jeremy, Leo, David and Philippe for contributions to this post)