Fun with reflection in C++

So yes, this is the first post on this blog with the tag “windows”. I happened to buy the Surface Book 2 laptop last year, and somehow felt like giving Windows a try after all this while.

It’s been a few months with this setup, and I am surprised at how well it has worked out for someone who once swore by Linux, and never considered using any other distribution. The primary credit for that goes to Windows Subsystem for Linux, and the fact that I can run a full fledged i3wm inside it.

This article shows how to solve a seemingly tough C++ hierarchy problem with some simple ideas using templates. In short, we will discover the need for functions which consume and return types (obviously such functions only matter at compile time), and see how such functions can be implemented. Basically, the very basics of type level programming.

Riding a bus back home; Green fields, grey skies, and a blank slate. ...

case (what_are_you_here_for) of
  HackWhatsApp -> "be gone!"
  HackFacebook -> "go away!"
  Else         -> "Hi!"

As I’m about to graduate with a Computer Science and Engineering degree from IIT Kanpur, I have noticed the lack of awareness and direction among many students who could otherwise have become valuable members of the programming and hacker communities. This document should serve the purpose of providing hints and potentially-interesting pursuits, in the general direction of becoming better programmers, coders and hackers.

Haskell is a tricky language to begin with, with a learning curve somewhat like this:

There are dozens of really great Haskell tutorials, which teach functional thinking, haskell syntax, type theory. I repeat, they’re great. And you can spend hours playing with functional concepts, types et cetera, even when you’ve gone through only a small subset of the language.

If you read such blogs, you would have been told that ghci is your best friend. This article will attempt to change that.

If you’ve tried to do CI builds of Haskell projects using Travis/Gitlab/Jenkins, you would know the pain of long build times. Haskell builds are infamously slow, and if you require pandoc or gtk or other such large packages, your build may often even timeout on some of the free CIs. Caching makes this better, of course, but it is sometimes difficult to set up, and sometimes it is simply not available/possible.

This is especially irritating if your static blog is written in Hakyll, and is built with CIs (like this one). Hakyll requires pandoc, and most builds end up taking somewhere near an hour. This post will demonstrate a way to massively speed up time-consuming haskell builds like that in a neat way.

This post will attempt to convey some real-life examples and tricks, which may serve as a quick and dirty primer to monad transformers. In any real-life software written in Haskell or related languages, Monad Transformers are priceless if you want to take advantage of the various non-IO monads available.

This post will draw heavily from my recent experience while implementing a blockchain protocol in Haskell.

If you’re using ElasticSearch, elastic4s is among the most neat DSLs out there. Recently, ElasticSearch decided to deprecate the Transport client, and remove it from v7.0.0 onwards. This also meant that HTTP Client became the preferred client since v6.0.0.

ElasticSearch also defaults to using SSL for the HTTP connections nowadays. It is also the (non-configurable) default when you’re using ElasticSearch-operator for easy deployment on Kubernetes. What’s worse is that it generates certificates for ES automatically, but doesn’t export the Certificate Authority keys used for the same. elastic4s does not allow using insecure SSL easily right now.

Calling C from Haskell is easy. Calling Golang from C is easy too. Then why should calling Golang from Haskell be tough? Yet, I could not find a single document / blog on this topic. While doing this, I also explored the possibility domain of library linking in Haskell.

My latest project (in Haskell) required a cryptographic protocol (Verifiable Random Function), whose implementation I could only find in Golang and C. The Golang ones seemed better maintained, self-contained, and understandable. So, I took the easy way out, and wrote a binary using that source code, allowing me to call the binary from Haskell (taking care to marshall the input and output binary data as base64 strings). Of course, this was ugly, and I got a (mostly) satisfying solution working, which did not have to launch a separate process for this simple task....

About one and a half years later, I finally thought it is time to reinstall Windows for completeness sake (don’t judge me please). Little did I know that I would be opening a pandora’s box.

So I never really understood the concept of EFI, or the difference between BIOS/UEFI; and yet, I have played around with bootloaders for quite a while now. I somehow managed to survive ...

Now that I’m back from the US, the extravaganza that is Google, reminiscing back to those days has made me finally decide to pen down my experience in the Cloud city, working on Cloud.

For context, I interned at Google Seattle, the third largest Google office in the US. The Seattle ...

Recap

For those who haven’t read the previous posts part 1 and part 2, this is a challenge which came up while trying to develop a secure version of a platform called Puppy Love...

So, after months of worrying, I had finally landed an internship position at Google Seattle, in the team of my choice. But before I could stop being lazy and sign the offer letter, something happened ...

I learnt a couple of nice scheduling algorithms in my Operating Systems class last semester. They seemed like an interesting bunch, but it was not generally clear whether their performance would be good.

Now, what better a way to understand them than by coding them up? ...

Recap

For those who haven’t read the previous post, this is a challenge which came up while trying to develop a secure version of a platform called Puppy Love. The introduction and the algorithmic challenge, taken from the previous article:

Too lazy to learn to use the awesome cmus, and living on an (very regrettably) extremely unorganized music library since I came to IIT Kanpur, yeah that’s me these days when it comes to music. Without the likes of Spotify in India, I’ve been living on YouTube since more than 2 years, when I used to have a fully organized music library back in my school days.

Having a very dynamic (and mostly incomplete) music library, I was constantly being annoyed having to import folders, sort some, organize others. What would be ideal in such a scenario is a way to live in the shell itself, but have the freedom to easily search for music files and play them. ...

NOTE:: The algorithm used has been re-worked, and changed since this article was written. Expect a new article with the formal algorithm soon :)

Update: The new article with the latest algorithm is here on my blog. Do read that article as a follow up!

The queerly named Puppy Love platform has been running in my university since 2014, meant to help shy nerds meet their crush, made my the Programming Club (of which, I happen to be the current coordinator)...

After a really late start to my undergraduate project (UGP) this semester, I finally started working on something we call moVi.

First off, if the idea reminds you of mosh - Mobile Shell by Keith Winstein and Hari Balakrishnan of MIT, it is not a coincidence. I’d loved their paper called Mosh: An Interactive Remote Shell for Mobile Clients, and moVi is in a way taking their idea forward...

Distributed network connections :)

Solving a self-posed problem :)

Try this next time you play pool

My first 100+ stars Github project

Experience and fun abound!

Finally put them to the test!

The ups and downs of the most whacky Linux journey I've had

Beginner guide to foraying into coding

Documentation for my esolang written for Chaos'16

Super condensed installation experience

How I got about with the excessive stress on my fingers due to Emacs

Shifting to Hakyll

The roads still diverge in the woods..

Quickfixes for battery backup on Linux

Moving on to..

An outpouring of thoughts about our life-choices

Haskell + Tiling = Perfection

Installing Syslinux/GRUB2

TLDR; It isn't just app-dev

Bloatware goodbye

No more 'sudo vim'

Joys of Tiling Window managers

Story of my first year at IITK

Life in the terminal

The --git-dir flag

Getting VirtualBox running in Arch

A beyond-the-vimtutor tutorial