Codaholic

Purpose Is Invariant

Thu, 02 Apr 2026 19:14:44 +0530

Recently I read a statement by Dr. Timnit Gebru that lodged in my head for a while -

“The purpose of a system is what it does.”

Apart from the critique that it is of so called “AI” systems we’re building today, it got me thinking about “purpose” in general.

Modular Arithmetic in Lambda Calculus

Sat, 28 Mar 2026 10:59:29 +0530

Recently I got curious about p-adic numbers and was wondering how to construct them just using lambda calculus. Why? No real reason except to entertain myself. I realized that to do that I need to first represent modular numbers – i.e. numbers as equivalence classes of the natural numbers – and the arithmetic around them before I can proceed to do this. So this is a follow on to the earlier workout involving paired up functions and their inverses applied to representing integers - in Church-Brahmagupta numerals.

CS edu and 'AI coding agents'

Fri, 20 Feb 2026 16:15:37 +0530

Damn! Not a day goes by without pondering over the nature of CS-ed going forward, given “AI coding agents”.

Status: DRAFT THOUGHT DUMP

And a Magnetic Field Appears

Thu, 19 Feb 2026 21:06:40 +0530

I recently thought-encountered a physics situation in which all charges appear stationary and yet a magnetic field appears. Here I’ll try to examine this situation in a few different ways.

Grokking Fermat's last theorem

Wed, 17 Sep 2025 21:14:53 +0530

One day I just happened to wake up thinking of Fermat’s last theorem and an urge to try and get a feel for why it is plausible at all. I don’t have the math chops to grok Wiles’ proof, but was just reaching for something which could suggest to me why it might be true at all. This is what I came up with.

Pascal's Determinant

Thu, 04 Sep 2025 07:21:54 +0530

Status: Draft (and will likely remain so due to the spirit of the thing)

I came across mathematician Timothy Gowers’ youtube video - A strange determinant some time ago.¹ In that video, he captures in real time his approach to a maths problem he hadn’t solved earlier. I really appreciated what he did there as this has been inspirational at so many levels and I’ve been citing this as an example of the attitude it takes to work on problems of comparable intellectual nature.

PLHCI - muSE's 'the' and 'it'

Mon, 25 Nov 2024 06:24:02 +0530

Will Crichton in Evaluating Human Factors Beyond Lines of Code recapped and outlined how programmers are users too and so programming languages need to be looked at through the HCI lens. He suggests using more precise vocabulary than “usability” and mentioned the cognitive dimensions of notation paper as providing some to consider. I thought it might be a useful exercise to try and describe muSE’s the and it constructs (ref) through that lens … as practice.

GPU friendly approximate matrix exp and log

Thu, 01 Aug 2024 03:49:18 +0530

Matrix exp and log calculations typically involve eigen-decomposition which is not very GPU friendly. For matrices with “well behaved” eigenvalues, the calculation approaches in this post seem to work sufficiently well without using eigen decomposition or matrix inverse.

That's odd

Sun, 21 Apr 2024 06:50:02 +0530

Sort of a fun “what if?” question in physics – What if we considered gravity to be approximated by a weaker “secondary” force in addition to the usual attractive force … similar to how the magnetic field relates to the electric field, and let it obey similar equations?

Nerd sniped!

Mon, 15 Jan 2024 22:38:31 +0530

Ok, I was nerd-sniped by the problem at https://xkcd.com/356/ . But I’m wondering if I managed to survive it somehow.

On the Pythagorean "theorem"

Sat, 11 Nov 2023 14:55:08 +0530

(Status: draft)

I’ve long held a view in my mind that the very well known Pythagorean “theorem” is not a “theorem” – in the sense of being able to be derived from a set of axioms through logical deduction. I want to jot down this thinking here because I think it is important for pedagogical reasons … but mostly I just want to get it off my chest even if the mathematical community considers this blasphemy. So I shall refer to this using “theorem” in quotes throughout this writeup.

Understanding Measurement

Sat, 15 Apr 2023 14:48:11 +0530

I’ve never quite felt that I understood what “measurement” means in quantum mechanics and my recent engagement with quantum computing surfaced this rather starkly. I’m not talking at the handwaving level of “wavefunction collapse” and such esoteric things. I just want an ordinary close hand-lens view understanding of what measurement is, even if incomplete at some level. This post is an attempt at that. If any reader thinks I should read up X/Y/Z to understand this, I’d much appreciate any links/references.

Deep Type (2016)

Fri, 03 Feb 2023 02:42:00 +0530

(This post was originally posted on the Imaginea blog on 27 May 2016. That blog now no longer exists, so I’m reposting it here. I have The Internet Archive to thank for keeping a copy of the text and my colleague Srikant Patil for his help recovering the images originally presented in this post from an archive.)

Generating values that fit a probability distribution

Tue, 31 Jan 2023 09:13:20 +0530

Constrained randomness is useful in adding a dash of variety to computer composed music. Picking values that fit a parametric probabilty distribution whose parameters are used for control is therefore a common case. Here I describe how to do that given access to only a uniform random number generator in the unit interval.

The Fourier Transform as a number

Sun, 15 Jan 2023 19:27:12 +0530

There is no dearth of explanations of the Fourier transform on the internet. Being a believer in understanding a concept from as many perspectives as possible, I welcome all of them. Here I offer yet another perspective that is “intuitive” in its own way and yet is not something I’ve seen presented often or presented in yet more mysterious ways.

Techie Kurals

Sat, 26 Nov 2022 18:15:50 +0530

Kurals are posted in public transport in Chennai - trains as well as buses. When taking them pre-covid to work, I used to amuse myself by translating them into techie parlance. These are gathered from my tweets. Maybe I should expand the collection and maybe I will, but for now, here it is. I feel the fun of doing this is spoilt if I provide the actual translation in English too.

Ranking emissions by country

Sat, 29 Oct 2022 11:37:48 +0530

In issues of policy and negotiations between countries on actions to be taken to mitigate climate change, the country-level figures that get discussed are either total emissions or per capita emissions. While total emissions is an important figure, per capita emissions gets all the attention. I’m starting to think that might be the wrong number to focus on.

A note on Alain Aspect's 2022 Nobel prize win

Sun, 09 Oct 2022 13:04:28 +0530

(This note on Alain Aspect getting the 2022 Nobel prize was shared by Prof. Sivakumar Srinivasan of Krea University. I’m posting this note here with his permission. I’ve taken a bit of liberty to split into paragraphs for easier reading. No other changes to his note.)

Church-Brahmagupta Numerals

Mon, 15 Aug 2022 18:45:29 +0530

Alonzo Church’s insight that lambda is sufficient to express all of computation is a non-intuitive stunning revelation. Showing that numbers can be represented using lambda alone using what’s come to be known as “Church numerals” is also brilliant. However, subtraction was a problem with plain Church numerals. Kleene solved that by using a pair of numbers instead. However even Kleene’s construction doesn’t give us a representation for negative numbers. Here we’ll look at a possible way to use Brahmagupta’s formulation to represent integers using lambda.

Transformer

Wed, 08 Jun 2022 19:37:38 +0530

THIS IS A DRAFT v1 as of 9 June 2022. Posting it early. Beware of bugs/errors. Will remove this notice once they’re cleaned up. Will also post full code soon.

I present the transformer architecture from ground up in Julia in this post. While my main purpose is to understand it in all detail without relying on any framework, I’m also hoping to try this out a way to teach machine learning … i.e. assuming whole program gradient calculation as a primitive. I won’t be explaining the why of the transformer architecture – for which I refer to Jay Alammar’s awesome tutorial – but mostly the how.

Odd and even numbers

Thu, 14 Apr 2022 19:02:20 +0530

This is a post by my kid, His first post! The rest of the text below is his attempt at explaining odd and even numbers.

Patterns

Fri, 18 Feb 2022 20:00:00 +0530

My kid’s math teacher recently posted a puzzle for the parents that got me down a rabbit hole of sorts and made me reflect on a number of things. This post is about that … and I mix the math and programming bits. I describe the puzzle in the first section and then the rest reveal aspects of the solution. So if you want to avoid the spoilers, you should stop reading after the first section.

Dual Vector Spaces

Tue, 18 Jan 2022 12:35:37 +0530

When talking about vector spaces, the notion of a dual vector space seems to often be introduced via postulates, such as in the excellent theoretical minimum series by eminent physicist Dr. Leonard Susskind. While that’s fine, I like an approach using linear functions, which I’ll present here. I learnt this from somewhere obviously, though I don’t recall where from.

Fairness in TLA+

Wed, 09 Dec 2020 23:22:21 +0530

As a TLA+ newbie, I found the fairness (weak and strong) formulae in TLA+ a bit hard going initially, so sharing the way I managed to wrap my head around it in case it is of help to others. What I’m hoping to get to is to be able to “read” the formulae in a chunked manner so that they make logical sense to me.

Inai: REST in the Small

Mon, 23 Nov 2020 11:17:32 +0530

(originally posted on the Imaginea Labs blog - https://labs.imaginea.com/inai-rest-in-the-small/)

The Inai project (forked here) began as a light hearted attempt to explore the consequences of bringing REST principles to organizing components within a single server node. It started off with the following question -

Given we know that REST principles are useful to organize the development, deployment and evolution of large collections of services, would those principles be useful in the small - i.e. within a single process?

The Calculus You Actually Need for Deep Learning

Fri, 02 Oct 2020 00:28:46 +0530

The Matrix Calculus You Need For Deep Learning (MCYNDL) is a great summary of what you need and expands starting from pretty much the basics. However, I’ve always felt that introducing the index notation used in physics can help simplify what looks like complicated math, even in that simplified intro. So here is my attempt at re-presenting the material in that paper, but using the simplified index notation. I think good notations are technology for the mind because they let you think and work with things that you otherwise might find too cumbersome or complicated to deal with.

Speculative: SciML for Physical Modeling Synthesis

Mon, 10 Aug 2020 15:54:52 +0530

Tools in the “Scientific Machine Learning” (SciML) space have been getting more sophisticated and general purpose. While going through some material regarding “universal differential equations”, I couldn’t help dream up potential applications to tough problems in physical modeling synthesis of musical instruments .. particuarly interested in the vina family of instruments. Noting down some speculative thoughts here that I hope will refine and be replaced with more accurate ones as I learn more.

The await-on-need Pattern

Thu, 26 Mar 2020 11:18:05 +0530

The async/await facility in ES5 is perhaps the single biggest readability boost to async code in Javascript - both in NodeJS and in client-side JS code. With async/await, code that does async activities starts to read like synchronous code with the keywords async and await thrown in at appropriate points. But don’t lose sight of opportunities for concurrency while settling into the comfort zone of synchronous-looking code.

I'm LisP. I'm inevitable.

Wed, 19 Feb 2020 18:30:00 +0530

This is a stub post linking to material presented during my talk titled “I’m LisP. I’m inevitable.” at the first Chennai Clojure meetup at Pramati Technologies.

Talk: the Nuts and Bolts of Webassembly

Sat, 24 Aug 2019 10:00:00 +0530

I gave a talk at the “Mixed Nuts @ Pramati” meetup on 2019-08-24 10am-12pm on WebAssembly. This post contains notes from the talk - sort of almost-transcript.

Simul-posted at https://labs.imaginea.com/talk-the-nuts-and-bolts-of-webassembly/

Abstraction is the root of all evil

Sun, 11 Aug 2019 15:44:48 +0530

A prized principle of design is the hiding of unimportant details from the users of a product that enables them to work with it without getting overwhelmed by its possibly complex inner workings. This act of deciding that something is unimportant and hiding it behind a simpler facade is what abstraction is about. In this sense, abstraction, when it works, is considered A Good Thing™.

Prolog Is Magic

Tue, 16 Jul 2019 20:58:34 +0530

It’s hard these days to impress kids with stuff computers can do that felt like magic back in the early days. Turtle graphics, even the venerable Scratch don’t have the wow factor from the get go because .. the kids have seen too much already. Here is how I (re)discovered something magical in a moment of resistant engagement with my 6-yr old when he persistently asked me to “teach him how to work on a computer”.

Good Ideas in Programming

Wed, 20 Mar 2019 09:00:00 +0530

Collecting a bag of what I think are good ideas in the history of programming, which lead to better thinking about system design, implementation and evolution.

Note: This post will continously be edited to include ideas as they come to my mind as worthy of being included here. Also, the ideas are in no particular order and this is just a brain dump.

Automatic Differentiation: Higher ranked beings

Wed, 13 Mar 2019 22:35:01 +0530

(Status: Draft)

We saw how we can try to calculate derivates of a function while evaluating the function in the first and second posts on automatic differentiation. Those dealt with only functions of a single real number. While that is illustrative of the approach, it was merely warm up so we can deal with differentiable functions of multiple variables that yield multiple values - i.e. vector valued functions of vectors … or more generally, tensor valued functions of tensors.

Automatic Differentiation: Dual numbers & Taylor numbers

Tue, 12 Mar 2019 17:38:57 +0530

In the earlier post, we saw how we can calculate the derivative of a function as a function itself. We may not need to do that, but may want the value of a function’s derivative to be calculated while the function expression is being evaluated.

Automatic differentiation

Fri, 08 Mar 2019 23:36:50 +0530

At Pramati Chennai, we’ve been having a series of sessions on math. The purpose is to try and connect many concepts usually considered as separate. We’re currently on a track to understand functions of multiple variables and their calculus.

Along the way, I thought it might be a good idea to try and introduce automatic differentiation in a programmatic way so people have a taste of how to precisely capture their ideas. This is not an attempt to implement the AD algorithms (at least not just yet), but to make the key idea concrete.

A hypothetical conversation with an 'imperative programmer'

Thu, 07 Mar 2019 17:42:11 +0530

(This was originally written on May 25, 2015. Publishing it ‘cos a former colleague actually recalled it after all this time when even I had forgotten about it.)

Talk: Machine Learning as extreme TDD

Thu, 07 Mar 2019 10:14:41 +0530

I gave a talk last evening at a meetup at Navis giving a soft introduction to machine learning for an audience of mostly developers and QA engineers. I’m sharing the slide deck and also some corrections of mistakes I did in the talk.

async/await subtleties

Thu, 03 Jan 2019 12:51:44 +0530

ECMAScript’s new async functions and generators simplify working with concurrent I/O code. While they work hand-in-hand with Promises, there are some subtleties that either seem to be underspecified in the language or not talked about much.

Integers

Fri, 14 Dec 2018 15:56:10 +0530

My son is learning about integers at school. It is quite a challenging topic to come to, especially as, thus far, for him, trying to understand it purely based on the familiar is both a necessity and a tough challenge due to the novelty of the idea.

Hodja on Debugging

Mon, 10 Sep 2018 19:00:25 +0530

I loved Naseeruddin Hodja stories when I was a kid. Heck I love them now too. They give me a good laugh and, as is common with good humour, manage to point at some truth once in a while.

One of these is a story where Hodja is searching for something in the garden. His wife asks him what he’s searching for and he replies he’s searching for his ring. She then asks him about where he’d lost it. He replies saying he’d lost it in the bedroom. Puzzled, she asks him why then is he searching for it in the garden. Hodja replies “because it is brighter here”.¹

I guess there is more context to that story than I can recall - perhaps as an allegory referring to an earlier event involving his wife.²

Filter Theory in Physics Notation

Fri, 07 Sep 2018 11:01:45 +0530

I happened to have picked up quantum mechanics from Feynman’s lectures and Dirac’s book before I got around to my main stream theory of linear filters during my B.Tech. So I went through a somewhat weird path of understanding the math around filter theory based on the quant-mech math I’d picked up. I do think it is clearer than the way linear filter theory books deal with the topic, especially due to an explicit notation for a “signal” in the abstract that is independent of “a representation of a signal”.

Here I capture a gist of how it went into my head. Note that I’m not aiming for mathematical rigour, but more as an illustration of how good notations are technology for the mind - simplifying our ability to reason in a domain.

Channels with async and await

Fri, 06 Apr 2018 20:52:00 +0530

async and await are, I think, the best thing to happen to Javascript, though I’d very much like something like sweet.js so I can invent it when I needed it most. However, I mostly see them being described in terms of promises. Here, I show how you can implement CSP style channels using them without using promises.

Warranties for Smart Contracts

Tue, 06 Mar 2018 22:29:33 +0530

(Cross posted from Imaginea Labs).

The distributed ledger protocol used by blockchains has resulted in systems where we do not have to place trust in particular parties involved in maintaining these ledgers. Moreover the ledgers are programmable with “smart contracts” - transactors whose state changes are recorded and validated on the blockchain. A collection of smart contracts describes a system that is expected to ensure certain invariants relevant to the domain are upheld. For example, an election system is expected to maintain voter confidentiality. While the code that describes these “smart contracts” is open for anyone to read, those who’re participating in the systems run by these smart contracts are not in general competent to evaluate them, with the OSS community being the sole eyes on the contracts being deployed. In this post, I examine how these smart contracts can provide “warranties” that are easier to ratify and describe clear and automatic consequences of violating the warranted properties.

Blockchain apps must be closed systems

Thu, 01 Jun 2017 00:09:00 +0530

Blockchain tech, especially smart contracts, are the hot new “internet”. Post the creation of Bitcoin, we’ve seen the rise of the public smart contract system Ethereum and several private systems like Linux Foundation’s Hyperledger. These distributed ledgers have become the brand new foundation to build apps on. This is as app developers hope to leverage the additional trust that these ledgers are supposed to provide by virtue of their distributed nature.

(Cross posted here from blog.imaginea.com - Blockchain apps must be closed systems)

Forget password

Sat, 29 Apr 2017 00:09:00 +0530

Can we have a signin/signup flow that is email-based and passwordless similar to a “forgot password” flow but where the URL will work only for the initiator, and only once per signin? This is the scheme I’ve implemented on Patantara and I describe its innards here.

On tech interviews

Thu, 23 Feb 2017 00:09:00 +0530

Recently, many techies have spilt words against doing the Google interview process. Broadly they feel their real and demonstrated abilities are not being valued. The most famous of these cases is Max Howell - the developer of homebrew - being rejected in the interview. Following Google, Amazon and the like, much smaller companies have also begun to subject interview candidates to such “problem solving exercises” - either on a whiteboard or within test environments such as HackerRank where you can be rewarded for coming up with the wrong answer quickly instead of the right answer slowly. These same candidates would speak up against these companies as well, had they interviewed there. Is there a real problem with this interviewing technique or are these candidates crying sour grapes?

Did you guess or did you estimate?

Tue, 07 Feb 2017 00:09:00 +0530

When asking software engineers for an estimate of the time required to build something, I often find them guessing the time taken instead of doing the work to estimate it. Yes, estimates come with their own caveats but, like planning, if you don’t estimate well, you may not have an idea of what you’re actually dealing with.

Here is something that I did with my kid yesterday that illustrates the difference between estimation and guessing.

M.S.B.A.

Wed, 23 Nov 2016 00:00:00 +0530

Traffic in any major Indian city can seem crazy to an outsider. Crazy, scary, impossible, noisy, unruly, chaotic, .. and you can keep on rattling adjectives without ever ending up in a jam. Of these cities, Chennai is perhaps the craziest.

AI ... YO!

Tue, 01 Nov 2016 00:00:00 +0530

(This article was originally posted on out-of-office.)

The recent Wired interview between Joi Ito, MIT Media Lab head, Scott Dadich, chief editor of Wired and the US President Barack Obama on artificial intelligence brought many perspectives into one room. The discussion is a great read as it covers the morally ambiguous ground that we might need AI to inhabit when we put them into autodrives, the role of government in funding and checking AI research, and … Star Trek. As a techie (and trekie), it is hard for me to resist the temptation of having a general AI at my disposal. However, what would the big picture be like? Would we be much better off with general AI all around us? Would AIs end up taking over the world, as is usually painted in dystopian science fiction, leaving us to fight to survive … maybe? Would I want to be in a world with general AIs all around, or would I find that world wanting?

Beta abstraction for bottom up theory building

Sat, 06 Feb 2016 00:30:00 +0530

When we begin working on a problem, one of our main tasks is to build a theory about the problem space so that we can capture and communicate our understanding about it to others and to machines. Given that when we begin building these theories we might know only a few parts of the elephant and not the whole elephant itself, what chance do we stand to discover the whole elephant if our starting point is a few limited perspectives? In this post, I share an example of how to arrive at higher level theories about a domain via bottom up exploration using systematic beta abstraction.

This post is based on and reuses parts of a discussion on beta abstraction done in our SICP study group at Pramati, Chennai.

Did The Martian biologist eat his own shit?

Fri, 25 Dec 2015 16:15:00 +0530

In the movie “The Martian”, Matt Damon plays astronaut Mark Watney who gets stranded on Mars and makes history by practicing open defecation and growing potatoes using his own shit as manure on Martian soil.

Becoming rational

Sun, 13 Dec 2015 21:30:00 +0530

Dr. Venkataraman, in his lecture at the Univesity of Mysore last Friday, said that India needs to become more rational and less superstitious (emphasis mine). These are just words. What do they mean?

Towards reactive animation in Elm

Sun, 13 Dec 2015 08:17:45 +0530

ReactJS is gradually moving towards a purely functional style of specifying application views. In recent versions, you’re encouraged to use a pure functional syntax that maps a view’s props to the appropriate virtual-dom components. Combined with Flux, this approach is getting closer to what is already established in the Elm world, where it is referred to as The Elm Architecture. This is particularly visible in the increasing emphasis on working exclusively with props and avoiding state when rendering React components, and piping all inputs and events into the “dispatcher”.

Norman and Tognazzini on Apple and design

Sun, 29 Nov 2015 05:44:10 +0530

When Don Norman and Bruce Tognazzini write that Apple is giving design a bad name, you sit up and listen. They write that Apple has thrown away well established design principles and gone for the pretty and snazzy instead.

iOS animation notes

Sun, 22 Nov 2015 00:00:00 +0000

Recently, I had to work on an animated view for an iOS app. I built the view using explicit layer-based animations (CABAsicAnimation and brethren) in a separate app and it worked fine. Then I moved the view into the host application and all hell broke loose. After much fighting with the API, I finally arrived at the techniques needed to ensure that the animations work as intended irrespective of context. This post collects these notes as a list of recommendations to follow.

Intuition

Sun, 01 Nov 2015 00:00:00 +0000

Yesterday, I drove an automatic for the first time. When driving a manual shifter, my brain is on auto pilot - I’m seldom aware of my gear shifts and footwork. When I drove the automatic, all of this suddenly needed to be consciously done. So there was a bit of struggle I experienced with a supposedly simpler system. Bleh! The automatic drive is not intuitive.

Now, wait a minute. We know that folks who shift (ahem!) from automatic to manual face a harder struggle. In the software world, there is a similar hurdle faced by folks shifting between operating systems, and yet we see wars of the kind “my OS is more intuitive than yours”. What do people mean when they say something like that?

Talk @ JSFoo 2015: Orchestrating the Web Audio API

Tue, 22 Sep 2015 00:00:00 +0000

Slides (CC BY-SA 3.0)

Talk: Functional Thinking for Fun and Profit

Tue, 11 Aug 2015 00:00:00 +0000

These are elaborate notes on a “Tech Tonic” talk given at Pramati Technologies, Chennai, on 23rd July 2015. The organization of this post reflects the talk itself.

On net neutrality in India

Sat, 18 Jul 2015 00:00:00 +0000

The net neutrality debate in India largely lingers on what folks will have to pay for that they’re now getting for free, how much more it is going to cost them to do the same things they’re doing today, what will happen to the small business guys as the large guys take over with money power, etc. Even the (in)venerable AIB does more or less the same pitch in their now famous Save The Internet video. There is also the article on The Hindu pointing out the panel recommendations and they mostly have to do with who and what needs to be paid for and what is to be left untouched.

Much of this money-focused hoohah is a distraction on why net neutrality is important to us. If we don’t adopt a “we won’t touch the internet” policy, there is much more at stake than just a few people making more money than we think they should.

Melakarta workshop for children at Brhaddhvani

Thu, 23 Apr 2015 00:00:00 +0000

Workshop at Brhaddhvani for children this summer on melakarta system.

Closures all the way through

Thu, 02 Apr 2015 00:00:00 +0000

In A Mental Model for Variables and Closures in Javascript, I described an allocation based model that I’d used with some success to teach and understand the intricacies of closures, as implemented in Javascript engines. While we have plenty of tutorials on closures that describe what results are gotten under various conditions, with variables being magically “captured”, I’ve not seen many work through a mechanistic explanation of closures. To that end, here is the slide deck of a session I recently conducted which walked the participants through a mechanistic understanding of closures and objects, using the Chrome debugger. Read on to find out how to follow the deck and the rationale behind it.

Talk: Mathemusicking with children

Sat, 21 Mar 2015 00:00:00 +0000

I gave a talk titled “Mathemusicking with children: Doing math and music without telling them apart” at the C. R. Rao Advanced Institute for Mathematics Statistics and Computer Science on 14 March 2015, as part of a workshop on Math, music and nature.

Why I'm a vegetarian

Wed, 18 Mar 2015 00:00:00 +0000

Some years ago, I had a change of perspective on being vegetarian. The fact that I am a vegetarian was not the thing that changed, but it was the why that did.

Errors, recovery and async code flow

Sat, 11 Oct 2014 00:00:00 +0000

try-catch-finally style error management is common in many programming languages. Though the underlying mechanism of propagating errors up a “call stack” is alright from a development perspective, the common syntax ends up invariably mangling the code flow. In cspjs, a macro library presenting an easy-to-use syntax for working with async Javascript code, I attempted what felt to me to be a better way to fit error handling and recovery code into the statement-by-statement sequential flow of activity.

In Bye Bye Javascript Promises, I intended to present this key reason why I wrote cspjs - error handling and recovery specification that respects code flow - but I didn’t do a good job of presenting it. I attempt that in this post.

Biking to work in Chennai

Fri, 03 Oct 2014 00:00:00 +0000

I’d written quite some time ago about seriously giving biking in Chennai a shot. I’ve recently joined Pramati technologies in Chennai and have been biking to work (about 9km one way) almost every day for the past month-and-a-half. Here are some observations and an initial attempt at guidelines for people considering biking as a means of commuting in Chennai.

Two trends towards partial programming language freedom everywhere

Thu, 17 Jul 2014 00:00:00 +0000

Two common backends seem to be emerging that enable programmers to choose a language and system suitable for their work irrespective of whether they’re developing server side code or client side code. Programmers who develop services that sit behind communication protocols such as HTTP have always enjoyed the freedom to choose the programming language and system that best supports what they need to develop, because clients who use system requirements placed by these languages do not get passed on to clients who make use of these services. Client-side programmers have, however, had limited options when it comes to programming language choice for various reasons, the most significant of which is perhaps accessibility to APIs for doing various things on the client device. Hence if you program for iOS, pick Objective-C. Android? pick Java. Windows? Perhaps C# .. or F# if you’re adventurous. Web browser? You got Javascript. For once, two common performant backends - Java byte code and LLVM bit code - are emerging as the common ground enabling portability and hence programming language diversity.

Wash dishes. Don't collect garbage.

Sun, 06 Jul 2014 00:00:00 +0000

In computer science literature, “garbage collection” refers to the process by which unused computer memory is reclaimed for use by a program. Such memory is usually referred to as “garbage” and the “garbage collector” periodically runs to do this job. Though I understand the process to some extent, I’ve never been happy with the metaphor since it doesn’t help at all with suggesting possible techniques for doing the task and is just used to label this part of a programming system with automatic memory management. In this post, I explore “dish washing” as a metaphor for the same process and argue why it is a better one to adopt for teaching purposes.

Mathemusicking

Sat, 28 Jun 2014 00:00:00 +0000

Recent writing in the field of ethnomusicology has re-asked the question of “what is music?”. Christopher Small coined the term “musicking”, which to me expresses that there is no such thing as “music” that is apart from the act of “musicking”. Music and mathematics have shared a historical bond with each other - with mathematicians finding fascination in musical patterns and musicians relishing in artistic construction using mathematical patterns, more recently involving computational patterns. The relationship that both these activities bear to the functioning of human cognition also share great similarities. Mathematicians have long declared the activity of “doing mathematics” as a creative process that is not steeped in certainties, as a naive view of mathematics might suppose. Paralleling that, musicians also often demonstrate intellectualization of the activity of musicking that resembles a mathematical theory of the constructs that they are building. In consideration of such deep connections, in this essay, I explore the parallel thesis - there is no such thing as mathematics, there is only mathematicking - and where I name the joint activity “mathemusicking”.

Being the change I want to see in Chennai

Fri, 21 Feb 2014 00:00:00 +0000

Was it Gandhiji who said “Be the change you want to see in the world”?

There are quite a few things about Chennai traffic that I would like to see change … and where better to begin than with myself?

Bye Bye Javascript Promises!

Tue, 11 Feb 2014 00:00:00 +0000

In my previous post, I explored how programming with promises can be made close to programming with values. After some more work on it, and some learning from bluebird, I came to conclude that my brain doesn’t think well with promises. So I wrote a macro for Javascript that expands “tasks” into async state machines that communicate using channels (i.e. CSP). I want to talk about the specific options for error management implemented in the task macro.

Implementing CSP channels using Promises

Sat, 25 Jan 2014 00:00:00 +0000

Promises are the new old thing in the land of Javascript async abstractions, though they aren’t as good as CSP-style channels for async programming. In this post, I describe a channel implementation based on promises that attempts to bring some CSP-style programming abilities into the JS world … now, instead of in ES6.

Anchoring time in the body - 2nd edition

Thu, 03 Oct 2013 00:00:00 +0000

In part-2 of How to Practice Carnatic Music with a Metronome, I described some beginning exercises for the vina that combine meditation with practice of basic right hand plucking techniques that need early mastery. I described five such exercises for anchoring the flow of musical time in the body through breathing.

One problem with having so many exercises is that it isn’t clear to beginner students which one to pick that’s right for them .. and, to be fair, neither did I have a clear idea of which one would be good for beginners – if I were to pick one. Now that some time has passed since I came up with those exercises and some students have had the chance to try them out, I do have a better idea and I can suggest one.

How to practice Carnatic music with a metronome - Part 3: Role Inversion

Sun, 29 Sep 2013 00:00:00 +0000

Status: Draft

In part-1 and part-2, I covered some very basic techniques for “anchoring time in the body”. In this part, I illustrate a technique for practice that I call “role inversion” with a pallavi as an example.

How to practice Carnatic music with a metronome: Part 2: The (real) basics

Thu, 12 Sep 2013 00:00:00 +0000

Status: Draft

Part 1 presented internalizing “layam” or musical time as the practice goal for working with a metronome. In the course of teaching vina, I realized that practice with a metronome already requires a sense of time and if this has not been nurtured initially, it can lead to an aversion to practicing with one to gain mastery over time and an unhealthy reliance on it, even if warned as I did with Part 1.

Notation: Ganarajena Rakshitoham

Tue, 09 Jul 2013 00:00:00 +0000

How to practice Carnatic music with a metronome - Part 1: The Basics

Sat, 25 May 2013 00:00:00 +0000

Internalizing the flow of musical time, known as “layam”, is an essential aspect of the training of a student of Carnatic music. Though the adage “sruti mata, laya pitah” (“pitch is the mother and time is the father”) is oft repeated, what we find in practice is that a reference for the sruti (tonic) is recommended for and always used by even beginner students, but a comparable reference for time in the form of a metronome is almost never seen.

Fun with nine nadais

Wed, 22 May 2013 00:00:00 +0000

Here’s something fun done in Tala Keeper - a walk through of Nine Nadais in one big 36 beat cycle. If you’re viewing this on your iOS device, tapping that link will open it in Tala Keeper. If not, the pattern will play in another browser window in the free HTML5 simulator.

Tala Keeper 1.3.0 released

Wed, 13 Mar 2013 00:00:00 +0000

Tala Keeper version 1.3.0 is the first public release of a visual metronome for practicing music involving complex (or simple) time structures.

Taming the ScriptProcessorNode

Wed, 30 Jan 2013 00:00:00 +0000

The Web Audio API provides graph based API for audio generation and processing primitives with a focus on high performance and low latency. For custom processing that is not covered by the builtin native audio nodes, it provides a ScriptProcessorNode whose processing is determined by a Javascript function. Though the ScriptProcessorNode is presented like any other node type by the API, its behaviour differs from the other native nodes in some fundamental ways. This post examines some of these differences using a simple chime model as the use case, and derives some suggestions for the Web Audio API specification.

Exploring graha bhedams

Sun, 30 Dec 2012 00:00:00 +0000

Here is a demo web app for exploring rāgās and their bhēdams.

Scratch pad for text with diacritics

Thu, 27 Dec 2012 00:00:00 +0000

Roman text with a few choice diacritics are a common need when writing about Indian classical music. Creating unicode text with diacritics that can be ported between applications is in general a pain. So, I made a small in-browser app that serves as a scratch pad for common diacritics.

A critique of Tuna

Fri, 09 Nov 2012 00:00:00 +0000

Google has open sourced the Tuna set of effects used in their Jam with Chrome project. Here, I collect some thoughts about the code design decisions for their effects framework, since I myself have written Steller.

On eval and evil.

Tue, 28 Aug 2012 00:00:00 +0000

“eval is evil” has become a maxim repeated in the Javascript community. Douglas Crockford, in Javascript: The Good Parts, rightly advises against hidden and explicit uses of eval for security and clarity reasons. Now, I find eval useful to implement DSLs in Javascript. The in-browser CoffeeScript compiler wouldn’t be possible without eval (directly or indirectly). So, in this post, I wish to explore what appears interesting about eval that is relevant to building such DSLs.

Toy language using j-expressions

Mon, 30 Apr 2012 00:00:00 +0000

Posted a “stream of thought” compiler for a toy language based on the idea of j-expressions as a representation for ASTs.

Code
Docs

J-expressions

Sun, 15 Apr 2012 00:00:00 +0000

JSON has become a kind of de-facto standard for sharing data among services on the web. The Lisp folks have enjoyed this luxury ever since … well ever since McCarthy made the language and his student implemented an interpreter for it. What’s more, they have also had the luxury of using the same syntax for sharing logic .. and in fact take it for granted. This post is a proposal to bring that “luxury” to the web programming world.

Status: Draft. Comments welcome.

Creating DSLs in Javascript using J-expressions

Sat, 14 Apr 2012 00:00:00 +0000

Scheme and Lisp have for long had powerful meta-programming abilities due to the syntax of their language being the same as the syntax for the main data structure supported by the language - the humble list. These languages are therefore well suited for inventing smaller special purpose “domain specific languages.

Javascript, on the other hand, has a “full blown syntax” that makes meta-programming not for the faint of heart. One consequence of the lack of such ability is that developers have not had the benefit of the abstraction possible through small special purpose DSLs.

Here, I outline an approach for creating DSLs in Javascript using the now prevalent JSON format that is native to the language. The initial part tries to explain the kinds of scenarios in which one might consider building a DSL, which is important to have an idea about. Later, I get into the actual representation using JSON.

A mental model for variables and closures in Javascript

Fri, 13 Apr 2012 00:00:00 +0000

Closures and variables have a strained relationship in Javascript that causes much confusion among newcomers and results in hard to spot bugs even for experienced JS coders. It is good to have a clear and accurate “mental model” of this relationship using which you can correctly predict what would happen with any given piece of code.

I came up with such a mental model a while back and posted it on Hacker News … which I reproduce here.

Classes and Javascript

Thu, 12 Apr 2012 00:00:00 +0000

If you have been programming in Java and C++ for a while and are used to thinking about problems in terms of classes and inheritance, you may find yourself struggling with Javascript since it has only objects. This post is to – a) provide you with a perspective on why programming with only objects is powerful and b) show you how to translate the class-based concepts you’re used to thinking in into the Javascript world.

Social hash as identity

Tue, 03 Jan 2012 00:00:00 +0000

(This is a “brain-dump” post).

Many write-ups and studies on social networks and privacy issues talk about the risk of using one’s personal information disclosed within social networks for identity theft. That made me think about whether it is really possible for an identity thief to steal my entire social environment and history or whether such theft is simply an indication of how broken the current paper-world identity systems are in the digital age?

Enter the “social hash” – a short identification string that can be generated from the data in your social network’s history that is very highly likely to be unique to you and very difficult to duplicate in a “prove your identity” challenge.

Newcomb's problem and quantum physics

Sat, 07 May 2011 00:00:00 +0000

How would Newcomb’s problem look like in the physical world, taking quantum physics into account? Specifically, would Omega need to know quantum physics in order to predict my decision on “to one box or not to one box”?

iPad2 wish ..

Wed, 26 Jan 2011 00:00:00 +0000

Now that macworld is near, it is time for an iPad wish list.

I have only one item on it - and it is the addition of a wacom tablet-like stylus interface on top of the capacitive touch screen. Camera? Nope don’t need. I want a pad where I can draw and scribble with precision, flipping the stylus on its head to turn it into an eraser. Ah! That’ll be a heaven of a tablet with both touch and stylus support.

Photon polarization

Wed, 05 Jan 2011 00:00:00 +0000

Decoherence as projection discusses photon polarization as a phenomenon that can only be explained quantum mechanically even at the macroscopic level –

The Alternate Reality Kit

Sun, 19 Sep 2010 00:00:00 +0000

The term “object oriented programming” has degraded to the point where I no longer take self proclaimed OOP enthusiasts seriously. I don’t believe they know what they’re talking about … unless they bring up something … anything … about Smalltalk. If you don’t have a clue about what makes me go soft upon the mere mention of Smalltalk, check out this 1987 video demo of the Alternate Reality Kit. Makes you wish you had that on an iPad today doesn’t it?

Primes - Go vs. Haskell

Sat, 18 Sep 2010 00:00:00 +0000

Recently, a friend of mine pointed out a concurrent implementation of Eratosthenes’ prime sieve expressed in google’s Go programming language. I couldn’t resist trying a Haskell version of that same approach.

Randall Munroe (xkcd) likes these

Fri, 12 Mar 2010 00:00:00 +0000

Recently, Randall Munroe held a guest week where some of his favourite cartoonists drew for him on xkcd. (RM was going through a family illness.) I love xkcd, so I got curious about what RM likes and decided to jot down links to all of them I could find. Here they are –

xkcd – A tribute link to the ever brilliant RM.
Zach Weiner – Saturday Morning Breakfast Cereal
Jeffrey Rowland – Overcompensating
Bill Amend – Foxtrot
David Troupes – Buttercup Festival
Jeph Jacques – Questionable Content
Ryan North – Dinosaur Comics
E Horne and J Comeau – A Softer World
Nicholas Gurewich – The Perry Bible Fellowship
Kazu Kibuishi – Cooper
Chris Onstad – Achewood
David Malki – Wondermark
Jessica Hagy – Indexed