Ask HN: your biggest Aha moment as a hacker?

This was a long time ago, so I don't remember the particulars, but it was in a large Fortran-based CFD flow solver code. The code used a lot of dynamically-allocated arrays, and somewhere in there we had a bug that would occasionally manifest itself in a crash. The problem of course was that we couldn't consistently reproduce it. This was before the days of really good memory debuggers, or at least, before we discovered such tools, so the bug just kind of lingered on for a long time.

The day I finally tracked it down was a red-letter day, for me personally anyways.

Learning C trying to figure out how to deal with a large 2D array (a map for an RPG) on a calculator (limited RAM and program size) when it finally clicked what a pointer is. I was hooked from that moment on.

my biggest aha moment came when I realized that all of my aha moments come after rest or working on other things

A big "Aha" moment for me was that I could just grep the big scary tar.gz source code of a project. (And that the big scary tar.gz wasn't that scary)

Before that moment, I had to post a question to the project's forum or submit a bug report if I had a problem with a project. Then one day, all of a sudden, I realized I could just go ahead and grep the source myself and that the source wasn't scary. I realized that not only could I look at the code myself, but also that I had enough skills in general that I could follow along with other people's code.

Essentially, my "Aha" moment was actually exercising Freedom 1 from the four essential freedoms of free software.

It was my first programming assignment, actually. I was a co-op student, working in a factory. A database used to communicate between the fab area and the order/sales types, suddenly stopped working. The original author was no longer around. I have no idea why I got picked to fix it... desperation, I suppose. I vaguely remember that some poor secretary had to do everything by hand while I figured it out.

I plunged around stupidly for a long, long time. I called it a database, but really it was more like a process-- a collection of one-off tools, on a variety of machines, that slowly massaged factory data into a form useable by the front office.

Eventually I blundered my way to the solution. Reading the manual for one of the languages used, it mentioned using EBCDIC codes when writing characters. A little bell went off in my head-- somewhere I had read that another machine in the pipeline used ASCII encoding.

None of this meant anything to me, but I knew that all the programs assumed a certain line length, and defensively stuck in a line terminator character just to be certain. A little poking around revealed that, sure enough, somehow a single record of the wrong length had got into the original data file.

So in the end, changing a single character in a single program made the whole apparatus wheeze back to life.

It was a great moment for me, seeing how such a little thing could have such a huge impact. There was also a heady feeling to the fact that nobody around me seemed to have any idea what I was talking about-- they were just happy the thing finally worked again.

When I realized that I hadn't learned languages, I'd learned techniques, and I could just change languages given a bit of time to bootstrap and some common starting points.

Basically, paradigms were my Aha. Kinda lame, but apparently there are a lot of developers who haven't figured them out yet.

I am building my first web app and learning Ruby on Rails as I go, so I literally have Aha moments every single day. When I get something to work (that I've never done before) I literally jump up and down. The feeling of seeing an idea come to life is just unexplainable!

Discovering map while writing in scheme was enlightening! It opened my eyes to functional programming and more than made the all nighter worth it.

I was a goober used to test algorithms for a modem. I showed one of the PhD's a simplification, assuming that they knew of it. They didn't. It goes to show how simulation can lead to improvements.

I had taught myself HTML and Javascript as my first adventure into writing code. A PC gaming related sites I visited often started doing some dynamic pages with Perl (this was the late 90s), and I just thought that was the bees knees, so I went off to learn Perl. I wrote a simple guestbook style script for a little site I had, uploaded it, went to the browser and got a nice 'Internal Server Error'. I read every line of code I had written, couldnt find the error, then realized my FTP client was set to upload in binary rather than ASCII. Uploaded the script again in the right mode, went to the site, and it worked. I didn't even know the difference between the two at the time.

It's not really an 'aha moment' that's on the same level as others mentioned here, but it was the first script I ever wrote. Before that, the dynamic portion of the internet seemed like magic. I've been hooked ever since. :)

At my first serious job, I wrote part of the interface for an embedded product. Because we were a tiny company I helped assemble, shrink wrap and finally ship them. My Aha moment was when they finally left the warehouse and that real people would depend on our stuff. It integrated their security systems and has to work, real people would be affected by my work.

Going to a shell, telnet'ing to port 80 and getting back a bunch of HTML. At that particular time and level of knowledge that was a huge A-Ha moment for me.

Teh internet is just text sent over a series of pipes ;)

These are the biggest AHA! moments that stuck out for me

  1. Understanding recursion in C
  2. Understanding lazy evaluation in Scheme
  3. Figuring out how to implement lazy evaluation in C

A lot of superficial differences between languages melted away after that. Definitely a "level up" feeling as a developer.

1. When I first realized I could loop and conditionally branch inside it (my first programming lesson) to do interesting stuff.

2. When I got OOP, and later when I realized the folly of vicious mutability.

3. When I discovered FP, composability and the Turing machine.

4. When I lately realized that software development is a giant hack to solve various business problems. ;)

Understanding the Continuation-Passing Style transformation, and how it makes the internal state of the interpreter explicit.

When I first read the BSD Unix source code and realized in a way that I had not before that the kernel which ran my C programs was itself just another C program, compiled with the same kind of C compiler, debuggable with the same kind of debugger (in many cases).

1. When I grew up in Taiwan, I was an avid reader of a certain PC gaming magazine. In addition to the usual strategies and walk-throughs, every issue also contained hex editing guides for various popular games. I could follow the instructions well enough, but I didn't understand hexadecimal numbers, so it was just monkey-see-monkey-do. Then one day, while flipping through computer books at an underground store, I "got" hex numbers, and my mind was blown. A whole new game hacking vista opened up in my mind's eye.

2. While learning Clojure, I tried my hand at implementing the Lisp interpreter described in PG's "The Roots of Lisp" paper. There were many "aha!" moments along the way, but the biggest one came when I understood how I could define the "eval" function inside my interpreter, which allowed me to run a Lisp interpreter inside my Lisp interpreter (which was running in Clojure, which was running on the JVM, etc.).

1) When I discovered there was a general order to learning web development. Beforehand, learning web programming was a giant mess of half-complete youtube videos and inaccurate articles.

2) Nested loops. Awesome.

3) Finally getting it through my thick skull that using fewer different moving parts in hacking, design, learning, etc is a way to actually get things done that also impress people. Before, I dove in and tried to use all kinds of variation, inventions, hacks. Now I use those things as accents, not the foundation of anything I do.

Understanding db normalization - subsequently realizing normalization should also apply to code.

Attempting to implement conways game of life and accidentally creating mesmerizing mandalas made of ascii characters!

"getting" lisp, writing a lisp, Figuring out how to implement TCO, macro expansion, quasiquote etc. then doing it all over again!

Realizing that almost all programming is a form of macro expansion/parsing/compiling. (taking the plunge from generating html/sql/css to generating an entire language is seriously not such a huge leap when you think about it)

Picking up and reading the smalltalk-80 reference manual, lisp 1.5 manual, and SICP cover to cover. Wishing I was 30 years younger and then realizing I am infinitely grateful for the opportunity to just absorb all of the work that has come before me and build upon it.

APL - finally the magic of the characters I had only accidentally typed in dos when pressing alt + num keys were mine to wield! (seriously though I really dig APL and its children) The book that finally made it click for me was "APL With a Mathematical Accent" - highly recommended.

I wrote my own deployment scripts to deploy django-based projects. Before that, I used to deploy manually; it was a long, frustrating process that was error prone.

The "aha" moment being that it's just a bunch of scripts to automate mundane tasks, "how didn't I think of that before?". Everything really is just that. All the tools we use are just programs that automate things we'd have to do manually otherwise.

This is kinda embarrassing to admit as a programmer, but in my windows days, it never occurred to me that I could just write scripts to automate mundane tasks. It seemed like everything had to come from "real" companies or "real" projects. If no company made it, or no open-source project exists for it, then you're stuck doing it manually.

I also now realize that this is the mindset of the average company that has no clue what it's doing. They also think if a tool doesn't have a GUI, it doesn't exist. 'git' is not a real system because it's all from the command line.

Incidentally, I had that aha moment around the time when I was transitioning from GUI tools to command line tools.

Apart from every page in Cormen's Algo book (which I will ignore because of the share number of those), my biggest AHA moment was about 3 years back when I realized that I can say "return a,b,c" to return 3 variables in python. Till then I had been only using C++ and could not fathom that a programming language can be painless.

I guess for me, it would be to realize how all softwares are basically abstractions. and how even the most scariest/magical software is only the summation of many smaller (lesser scary) pieces.

It took me a while to remember mine. It was my first introduction to functional programming using JavaScript. I didn't even realize that's what I was doing but when I realized that I could write a function that returned a function my brain damn near exploded with possibilities.