Early in my time at Facebook I realized the hard way that I couldn't do everything myself and for things to be sustainable I needed to find ways to work with other people on the problems I cared about.

But how do you do that in practice? There are lots of techniques from various courses, training, tips... In this note I'm going to explain the technique I'm using the most that has been very successful for me: "casting lines".

So you want something to happen, let say implement a feature in a tool. The first step is to post a message in the feedback group of the tool explaining what the problem is and what you want to happen. It's fine if it's your own tool. The objective here is that you have something you can reference when talking to people, you can send them the link with all the context. It can also be an issue on a github project, a quip, a note... the form doesn't matter as long as you can link to it.

If the thing is already on people's roadmap or already implemented under a gk, then congratz, you win. But most likely it is not.

This is where you start "casting lines". The idea is that anytime you chat with someone, whether it is in 1-1 meetings, group conversations, hallway chat... and the topic of discussion comes close (for a very lax definition of close), you want to bring up that specific feature: "It would be so awesome if we could do X". At you see the reaction. If that person feels interested, you then start to get them excited about them building it. Find ways it connects to their strengths, roadmap, career objectives... and of course send them the link.

In practice, the success rate of this approach, in the moment, is small because people usually don't have nothing to do right now and can jump on shipping a feature that they never thought about. But if you keep casting lines consistently in all your interactions with people, at some, point someone will bite.

The more lines you cast, the more stuff are going to get done.

While this technique has been very effective at getting things done at scale, there are drawbacks to this approach. The biggest one being uncertainty around timelines. Unless someone bites, you don't know when something will be done. Some of my lines are still up from many years ago.

PS: while researching for this note, I learned that the fishing technique shown in the cover photo is called "Troll Fishing".

If you watch pro pool players, most of the time the game is super boring, if you don’t believe me, watch this video from someone that puts 152 balls in a row. What’s interesting is that if you were to look at each shot individually, most of them are easy. I can likely make the 152 pots he did in a row, if I didn’t have to care about positioning myself for the next ball.

The real talent of pro pool players is being able to not only pot the ball but put the white ball in a good position for shooting the next ball. When they play well, they “make the game easy” by having the white ball always in a good position for the next shot.

What this means is that if you see a pro player doing some crazy shot, this means that they “got out of position” in the previous ball. And in practice at this level, usually they did a mistake a few shots earlier and haven’t been able to correct the position back and it gradually amplified.

This is a really bad property when watching the game, so most tournaments introduce a 30s limit so you don’t let the players properly think through and increase the likelihood of making mistakes, and having to come up with interesting shots.

There are a lot of interesting strategies in order to get good at it:

  • Routes that avoid crossing “danger zones” (right behind an enemy ball)
  • Land in a place where there are multiple shots available next rather than a single one
  • Come into the line of the next shot so that you don’t need to be super precise with your speed
  • Remove all the balls next to each others so you don’t have to go up and down the table with longer shots

Now is probably the point where you’re asking yourself, that’s interesting but what does it have to do with software engineering. Well, I think that there are a lot of parallels with building software.

When I see people doing very visible and consequential actions, I find myself thinking that they are doing a “hero shot” and it must mean that they got “out of position” for the past few shots and now the only option that they have left is unsatisfying but there’s no other choice.

On the other hand, I see people appearing to somehow always be in easy projects where everything just works out fine and they deliver a lot of impact. I used to think that they were lucky, now I think that they are pro players and are able to plan multiple shots in advance and able to execute on their strategy.

Andres Suarez pointed me to some interesting code in the Hack codebase:

let slash_escaped_string_of_path path =
  let buf = Buffer.create (String.length path) in
  String.iter (fun ch ->
    match ch with
    | '\\' -> Buffer.add_string buf "zB"
    | ':' -> Buffer.add_string buf "zC"
    | '/' -> Buffer.add_string buf "zS"
    | '\x00' -> Buffer.add_string buf "z0"
    | 'z' -> Buffer.add_string buf "zZ"
    | _ -> Buffer.add_char buf ch
  ) path;
  Buffer.contents buf

What it does is to turn all the occurrences of \, :, /, \0 and z into zB, zC, zS, z0 and zZ. This way, there won't be any of those characters in the original string which are probably invalid in the context where that string is transported. But you still have a way to get them back by transforming all the z-sequences back to their original form.

Why is it useful?

The first interesting aspect about it is that it's using z as an escape character instead of the usual \. In practice, it's less likely for a string to contain a z rather than a \ so we have to escape less often.

But the big wins are coming when escaping multiple times. In the \ escape sequence, it looks something like this:

  • \ -> \\ -> \\\\ -> \\\\\\\\ -> \\\\\\\\\\\\\\\\

whereas with the z escape sequence:

  • z -> zZ -> zZZ -> zZZZ -> zZZZZ

The fact that escaping a second time doubles the number of escape characters is problematic in practice. I was working on a project once where we found out that the \ character represented 70% of the payload!


It's way too late to change all the existing programming languages to use a different way to escape characters but if you have the opportunity to design an escape sequence, know that \ escape sequence is not always the best 🙂

I'm working a lot with URLs that contain ids and very often, I made a mistake in one digit of the long id and end up with a completely different element. If I don't pay attention, then I end up looking at two elements thinking they are the same and am intrigued until I find out the mistake.

In order to avoid that, I wanted to know if I could make a sequence of ids where making one mistake would not give a valid id. For example, if you have the id 473, then you have to black list all the ids where the first digit is wrong (073, 173, 273, 373, 573, 673, 773, 873, 973) and the second being wrong (403, 413, 423, 433, 443, 453, 463, 483, 493) and the last one (470, 471, 472, 474, 475, 476, 477, 478, 479).

Here is the list of the first pseudo-numbers:

  1. 011
  2. 022
  3. 033
  4. 044
  5. 055
  6. 066
  7. 077
  8. 088
  9. 099
  10. 101
  11. 110
  12. 123
  13. 132
  14. 145
  15. 154
  16. 167
  17. 176
  18. 189
  19. 198
  20. 202
  21. 213
  22. 220
  23. 231
  24. 246
  25. 257
  26. 264
  27. 275
  28. 303
  29. 312
  30. 321
  31. 330
  32. 347
  33. 356
  34. 365
  35. 374
  36. 404
  37. 415
  38. 426
  39. 437
  40. 440
  41. 451
  42. 462
  43. 473
  44. 505
  45. 514
  46. 527
  47. 536
  48. 541
  49. 550
  50. 563
  51. 572
  52. 606
  53. 617
  54. 624
  55. 635
  56. 642
  57. 653
  58. 660
  59. 671
  60. 707
  61. 716
  62. 725
  63. 734
  64. 743
  65. 752
  66. 761
  67. 770
  68. 808
  69. 819
  70. 880
  71. 891
  72. 909
  73. 918
  74. 981
  75. 990

And here is a visual representation of those numbers:

For each digit in the number, we blacklist 9 other numbers. For a 5 digits number (eg 12345), that means blacklisting 45 numbers. For a 10 digits number (eg 1234567890), that means blacklisting 90 numbers. The number of blacklisted numbers only grows at a logarithmic scale.

In order to see how many numbers we lose, I plotted the ratio of pseudo numbers count compared to the real numbers. We can roughly keep one number every fifteen. But the good news is that the ratio doesn't fall off the chart as the numbers grow.

Looking at the numbers, they looked like to go from 10 to 10 but with some huge spikes and sometimes they were closer. So I plotted the difference between two consecutive numbers in a chart and it looks like the difference is centered around 10. But the variance is getting higher and higher as you move further.

I'm not really sure if this sequence can be really useful in practice but that was a fun week-end experiment. I hope it'll give you some, hopefully useful, ideas 🙂

Lately, I've been advocating to all my student friends to start a blog. Here's an article with the most common questions answered 🙂

What are the benefits?

Being known as an expert. The majority of my blog posts are about advanced Javascript topics. As a result, I'm being tagged as the "Javascript" guy by people that know (broad sense) me. Every time they have a question about Javascript or Web Development they go to me.

Expanding your relations. Through my activities with this blog, I had conversations with celebs such as Bjarne Stroustrup (C++), Brendan Eich (Javascript), Jeremy Ashkenas (CoffeeScript) and many other people that I didn't know before. No one in my close relations is deeply interested in what I am writing. But thanks to the internet, I can meet other people that shares the same interests.

Getting Recruited. As you become an expert in a field, people start to notice and will want you. My blog is barely known and still, I have received several job offers. However this happens at random, take it like a gift but don't expect it to happen, or it won't 🙂

Being better. I've been so much better at Javascript since I started writing about it. But maintaining this blog also helped me improve my writing skills as well as my English.

Benefits are long term. You should not start a blog and expect it to be rewarding the next week. A blog is a presence on the internet. During the first 6 months, I barely had more than 5 visitors per day, but this number slowly started growing as I wrote more articles and time passed. Now, I'm at 100 visitors a day. I'm still amazed to see that so many people come!

Who cares about my blog?

Your friends. The first thing I do when I am done writing an article is to paste the link to some of my MSN contacts that will be vaguely interested in. It is a powerful way to start a conversation with people you did not talk with for a long time. I often re-write parts of the article given the feedback I receive and it leads to great conversations.

People on the Internet. My girlfriend always says "If you thought about it, someone did it". On the same idea, I believe that the following statement is correct: "If you find something interesting, someone else does too". Here is a fact, there are over 100 visitors on my blog everyday. Google connects people with the same interests!

People that want to know about you. The extreme example is your recruiter, but it could be a co-worker or even just a friend. Your blog is the place where you can show who you are and what you are worth. It is much better than a resume as it isn't constrained by a strong standardization and a ridiculous 1-page constraint.

I don't know what to write

Projects you've done. The easiest way to start a blog is to write one article per school/personal projects you have done. Put a screenshot, a description of what it does and you are set. This way, if I want to know about you, I will quickly scroll over your blog and will see what you have done. If something interests me, I'm going to read the article more closely.

Techniques you have used. It is interesting to go over your projects and allocate one blog article for each technical problem you solved. For example, the project Guild Recruitment leaded me to write several articles such as Dynamic Query Throttling, Mysqli Wrapper, Search Optimizations. The latest eventually made me look deeper to write Sorting Table.

Follow-up a conversation. I am often debating with my friends on topics related to computer science. Those discussions are potential targets for a blog post! It is really interesting to go deeper and start writing about it. You'll get more arguments to crush your friends theories 🙂

Start writing and ideas will flow. Once you have an article written, it often generates new ideas. Now, every time I write some code, I ask myself if that would be worth blogging. If yes, I create a draft on WordPress for later. This way when I'm in the mood of writing, I have many things to write.

There are already many article on the subject, why should I write mine?

Influence people around you. I always love reading my friends blog because they are talking about subjects that I'm interested in but that I would not have willingly researched for. It helps expanding my Javascript-centric horizon.

If you write about it, it means you know it. For example I wrote an article about how to use makedepend in makefiles. It tells recruiter multiple things. I have experienced the problem of dependency management. I am confortable with Makefiles as I used them in a fancy way. This is invaluable compared to a Makefile entry in a resume.

Go deeper in the subject. I often find myself writing code pretty easily without too much thinking. Writing about this particular sexy technique in my blog more challenging. It requires me to state the exact problem I try to solve, think about alternatives, seek for already existing solutions ...

After the post has been written, I receive a lot of feedback. My friends almost always talk about how it would have been solved in their own language of predilection. They also provide more use-cases where the technique would and wouldn't work, leads to improve it ...

How long does it take?

Count one evening per post. I usually spend one full evening writing down an involved article like this one. However I think a lot about the subject in a passive way by reading related articles, thinking about it in my bed ... Articles that show off a project are much quicker to write, I'd say about 30 minutes.

Post as often as you want. When I have something I deeply want to share I write an article about it. Once I've written once, I often see myself writing some more about drafts I had. Then there is a period of silence. Overall, I'd say I write every two months, often during holidays.

How many articles. Each new article you write is not going to shadow the other but adds up. When I check my analytics, each article written slightly increases my daily viewer count. But even with one article a blog is worth it.

How do I start?

Install a WordPress. Even if you are a geek, I strongly recommend against you coding your own blog or using some nerdy blog software. I went over that myself and I found myself coding stuff every time I wanted to write an article. WordPress gives you all the tools you need to blog, and if you want to do something a bit special, chances are there's already an extension that does it.

Quickly write your first article. Don't spend so much time finding the perfect theme or installing many extensions you don't even need yet. The first article is the hardest! Write it down and send it to your friends. Listen to their feedback and instead of editing the article, write another article trying to fix those issues. Writing is hard so it'll take more than one shot to feel comfortable with it. The more you practice, the easier it will be.


If I managed to convince your starting a blog, please give me the link! I'd love to read about your stuff and may help you get started if you want.