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Tuesday, April 21, 2015

Between Poverty and Universality lies Structure

Lisp is worth learning for the profound enlightenment experience you will have when you finally get it; that experience will make you a better programmer for the rest of your days, even if you never actually use Lisp itself           —  Eric Raymond

In ancient times people set each other puzzles such as:

       Can God make a stone so heavy that he can't lift it?

These puzzles-of-omnipotence can be rephrased in theory-of-computation lingo:

       Can God compute the uncomputable?
       If he can, how is it uncomputable?
       If he cant, how is he God?

So what are those limits of/by structure?  Unsurprisingly related to God-el's theorem:
God-el's Theorem says that for any record player, there are records which it cannot play because they will cause it to self-destruct

And like record players what about programming languages whose abstractions can be arranged to break the language?

Structure is good because it reduces breakage; its bad because it imprisons us into precooked forms.

Following I explore the space between poverty and universality; a space which for want of a better word I will simply call structure, the most elusive being the structure of syntax.

Thursday, March 26, 2015

CS History 0

Are real numbers real?

Wait!! What does this have to do with programming? Or even computer science??

Sounds like angels-on-the-head-of-a-pin philosophy No??
NO!  CS came into existence because of this question!

Monday, March 2, 2015

Unicode: Universal or Whimsical?

Unicode Classification

In my last post, I wrote about two sides to unicode — a universal side and a babel side. Some readers while agreeing with this classification were jarred by a passing reference to ‘gibberish’ in unicode⁵.

Since I learnt some things from those comments, this post expands that classification into these¹.
  1. Babel
  2. Universal
  3. Legacy
  4. Unavoidable mess
  5. Political mess
  6. Whimsical

Thursday, February 26, 2015

Universal Unicode

What is the 'uni-' in unicode? According to the official records it comes from Unique Uniform and Universal.

Unicode starts out with the realization that ASCII is ridiculously restrictive, or the world is larger than the two sides of the Atlantic¹. This gives rise to all the blocks from Arabic to Zhuang.

However the greatest promise of unicode lies not in catering to this tower of babel but rather in those areas that are more universal. Yeah I know technically this distinction between universal and international will not stand up to scrutiny.

Tuesday, January 6, 2015

Unicode and the Universe

If you're trilingual you speak three languages, if you're bilingual you speak two languages, if you're monolingual you're American.

Mark Harris on the python list
Well if one reads that thread above, one would find that people were rather uptight with Mark Harris for that statement. And yet they have the same insular attitude towards ASCII-in-programming that Mark describes in Americans towards English (or more correctly Americanese); to wit they consider that programming with ASCII (alone) is natural, easy, convenient, obvious, universal, inevitable etc.

Is it mere coincidence that the 'A' of ASCII is short for American?

Friday, September 26, 2014


In the early 90s  I used gofer to teach FP in the introductory programming class at the university of Pune.  At first I used Miranda/Scheme, then gofer. I was also impressed with Dijkstra's philosophy of making function application explicit with a dot ('.') and decided to incorporate this into gofer.  This changed gofer was called pugofer.

The philosophy of these changes is here. Summary of changes is:

Tuesday, August 12, 2014

Universities starting with functional programming

Here's a list of some universities that are using functional languages to teach programming. As I find more data, it will be added. So please let me know (with links!!) what Ive missed – lists are particularly welcome, but individual universities is also welcome.  Also other languages that have some claim to being functional.
Haskell – official list (list)
At quora (also scheme and ML dialects) 
Carnegie Mellon 

Wednesday, July 9, 2014

ACM FDP – Invited Talk

I was an invited speaker at the ACM faculty development program (FDP) organized jointly by ACM and VIT Pune on 9th July 2014.
The stuff of my talk — and good deal of other stuff that I did not manage to cover for lack of time :D — is put up at github.

To view, you will need

Tuesday, May 13, 2014

Unicode in Haskell Source

After writing Unicoded Python, I discovered that Haskell can do some of this already.  No its not even half way there but I am still mighty pleased!

Tuesday, April 29, 2014

Unicode and the Unix Assumption

Once upon a time, file was a rich, profound, daunting and wondrously messy concept. It involved ideas like
  • record orientation
  • blocking factor
  • partitioned data sets
and other wonders of computer (rocket) science.

Then there came along 2 upstarts, playing around in their spare time with a machine that their Lab had junked. They were having a lot of fun…

They decided that for them File was just List of Bytes.
type File = [Byte]
Oh the fun of it!

Saturday, April 19, 2014

Unicode in Python

1 Introduction

Python has been making long strides in embracing unicode. With python 3 we are at a stage where python programs can support unicode well however python program-source is still completely drawn from the ASCII subset of unicode.
Well… Actually with python 3 (not 2) this is already possible
def solvequadratic(a,b,c):
    Δ = b*b - 4*a*c
    α = (-b + sqrt(Δ))/(2*a)
    β = (-b - sqrt(Δ))/(2*a)
    return (α, β)

>>> solvequadratic(1,-5,6)
(3.0, 2.0)
Now to move ahead!

Tuesday, September 17, 2013

Haskell: From unicode friendly to unicode embracing

Doesn't λ x ⦁ x  :  α → α look better and communicate more clearly than \ a -> a :: a -> a  ?

What are the problems with the second (current Haskell) form?
  1. The a in the value world is the same as the a in the type world -- a minor nuisance and avoidable -- one can use different names
  2. λ looks like \
  3. The purely syntactic -> that separates a lambda-variable and its body is the same token that denotes a deep semantic concept -- the function space constructor
APL was one of the oldest programming language and is still one of the most visually striking.  It did not succeed because of various reasons, most notable of which is that it was at its heyday too long before unicode.

While APL is the first in using mathematical notation in programming, Squiggol, Bananas and Agda are more recent precedents in this direction.

In short, its time for programming languages to move from unicode-friendly to unicode-embracing

Some stray thoughts incorporating these ideas into Haskell.

Tuesday, September 10, 2013

Computer Science: Technology or Philosophy?

A computer is like a violin. You can imagine a novice trying first a phonograph and then a violin. The latter, he says, sounds terrible. That is the argument we have heard from our humanists and most of our computer scientists. Computer programs are good, they say, for particular purposes, but they aren't flexible. Neither is a violin, or a typewriter, until you learn how to use it.
Marvin Minsky – Programming clarifies poorly-understood and sloppily-formulated Ideas

Computer science is not a science and it has little to do with computers. Its a revolution in the way we think and in the way we express what we think. The essence of this change is procedural epistemology — the study of the structure of knowledge from an imperative point of view, as opposed to the declarative point of view taken by math.
Mathematics provides a framework for dealing precisely with notions of «what is»
Computation provides a framework for dealing precisely with notions of «how to»

Abelson and Sussman — Structure and Interpretation of Computer Programs

Computer Science is no more about computers than astronomy is about telescopes, biology is about microscopes or chemistry is about beakers and test tubes.
There is an essential unity of mathematics and computer science.

Michael Fellows — usually attributed to Dijkstra

The above three quotes are interesting as much in their agreement – the irrelevance of computers to computer-science – as in the difference of emphasis: Minsky sees CS from the intelligence/learning pov, Fellows/Dijkstra as math, Abelson/Sussman as something contrasting to math…

So what actually is CS about??

Following is an article I wrote for a newspaper in 1995 on the wider-than-mere-technology significance of CS — reposting here for historical interest.

Monday, September 9, 2013

The Poorest Computer Users are Programmers

In the old days programmers programmed computers. Period.

Nowadays when everything is a computer, and the traditional computer is about a decade and half behind the curve, describing a programmer as someone who programs computers is narrow and inaccurate. Instead we should think of programmers as working at effecting and improving the human-X interface, where X may be 'computer'. But it could also be IT, or technology or the network and through that last, interaction with other humans.

Now the classic 'nerdy' programmer was (by stereotype) always poor at 'soft' questions like that:  Interaction? Synergy?! What's all that manager-PR talk to do with programming?

And so today…

Programmers are inept as users of computers

Some examples:

Tuesday, August 27, 2013

Apply-ing SI on SICP

Abelson and Sussman wrote a legendary book: SICP. SICP cover The book has a famous wizard cover. Unfortunately the cover misses some key content of the book.  What is it?

If we remove the other wizardly stuff, three main artifacts stand out on that cover:  eval and apply on the crystal ball and a magical λ.  Lets put these into a table

apply eval

The fourth empty square seems to stand out, doesn't it?  Lets dig a little into this square.