Skip to content

Latest commit

 

History

History
65 lines (48 loc) · 6.78 KB

challenge_box.adoc

File metadata and controls

65 lines (48 loc) · 6.78 KB
Raw

Spotlight on Opa app: box by Vimalkumar Jeyakumar

Try box!

For your convenience we’ve embedded the game in this post, but for best results we suggest you open it by following this link.

Interview with the author: Vimalkumar Jeyakumar

me: Can you tell us a bit about yourself? What’s your experience with web programming?
Vimalkumar Jeyakumar: I am Vimal, and am currently a student pursuing my PhD in Computer Science at Stanford University. I started web programming since my undergraduate days with PHP. After that, I had a chance to maintain a high traffic website for two of our college technical festivals, which also got me interested in web designing. I really like PHP as it’s very easy to begin, especially if you’re coming from a world of C/C++. But the exercise of building and maintaining a large website made me realise how much the web-admin has to keep in mind!

me: Favorite languages? Web frameworks?
VJ: Frameworks: After PHP, I started experimenting with Ruby on Rails and Django. I found Rails confusing at the time and learnt Django, on which I built a website to evaluate submissions for an online programming contest (much like http://spoj.pl). I had previously hacked on a similar website using PHP, and hence the benefits of Django were very clear; the framework helped me think differently about the application than mere requests, responses and database queries. I also ended up learning Rails and it has helped me understand how modern web applications are built.
The above frameworks like Django, Rails and mini-frameworks like Flask, Sinatra were quite different from another contending framework: GWT. It took a while to understand, but the approach of treating a webapp as a single application which gets later split into a client+server side component interacting with RPCs was impressive. I never really used GWT, but I liked the idea. And when I saw Opa, I could relate to some of its principles.
As you can see, I have tried several frameworks, with some understanding of the benefits of each. When faced with a project, I try to pick the framework that would best suited for the project at hand. But most of the time, I need something extremely simple. Hence, I really like the simplicity of frameworks like Flask/Sinatra.
Languages: I spend most of my time programming in C, as I do a bit of kernel programming. In userspace, it’s Python.

me: Can you tell us a bit about your submission for the contest? How did you come up with the idea? What are your future plans with respect to the application?
VJ: I stumbled upon Opa as a new web-app framework on Hacker News, but didn’t really find a reason to invest learning ``yet-another-framework/language'' until I came across the competition. I love competitions! Given the uniqueness of Opa, I was not looking for something totally new, but a nice application that would benefit from those unique features (so that I’ll actually learn Opa). I also thought the app should be easy to relate to and be simple so that I don’t get bogged down by complexity. Hence the idea of an anonymous, easy to use file sharing service, as:

  • it has real-time notifications (using the Network.Cloud construct)

  • it is extremely simple to understand; so I don’t have to think about sessions, user auth, and all that stuff! ;)

  • it stresses the database (to store files)

Currently, I have some ideas of features that I wanted to add for the contest, but couldn’t due to the lack of time:

  • Adding drag-n-drop feature.

  • Email/SMS notifications for added files (what if you forget your random box id!).

  • Instant previews for image files, instant streaming for video files, etc!

me: How did you like programming in Opa? (was it different than other technologies you know? Anything that you particularly liked? Anything that could be improved?
VJ: I have a soft corner for Functional Programming Languages, and it was nice to recollect my previous short stint with OCaml when I programmed in Opa. Pluses aside, here are some pain points with Opa:

  • Opa takes a LONG time to compile, really long.

  • Opa takes a LOT of memory to compile, hence my old Macbook pro just trashes and becomes unusable while compiling apps.

Fixing these two should make programming with Opa more fun! A few other cribs:

  • Access to low level functionality: I don’t believe abstracting everything away is the best choice. For example, I wanted to store the uploaded files on the disk, and not the database. I couldn’t find a file system API (or, maybe I didn’t look properly :-))

  • Documentation is good, but would be much better with short examples for quick understanding. Thankfully, due to Opa’s type system, I was able to figure out a way to compose functions.

  • A way to warn users about the automatic client/server separation''. Not all errors are captured by the current type system; I had a weird issue while testing, where my uploaded files would cause an XML error due to invalid characters when I loaded a page. I later realised that when I was manipulating the DOM, the function used a file'' object that contained the stored file data as well. So, every page load caused all the uploaded files to be transferred to the client browser!! That is no file-sharing app!! :-) A ``lazy'' approach to transferring values would have solved the problem. Is it possible to incorporate this into Opa?

  • It would be helpful if the documentation also has details about the low level implementation details. I firmly believe that knowing what goes on underneath is really important to building a nice application.

Pains apart, I think some of the great pluses of Opa are:

  • It has great abstractions to make an impressive start. The distributed database, not having to worry about consistency, request load balancing, etc., makes developer life easy. If your website becomes viral, chances are less that you’d have to rewrite it if you had chosen Opa over other frameworks!

  • It’s functional: Constraining a programmer to the discipline of a functional language is an investment that reaps benefits as the projects become much bigger. What I really liked about Opa is that many popular JavaScript libraries and CSS styling have been wrapped into a nice Opa interface that lets you think in Opa style.

  • Static typing helps catch most bugs at compile time rather than a stack trace at run time.

  • The client-server split is a great boon as well, because it’s hard to get RPCs right without using some reliable library.