Many may discount the idea of "best programming language" with "all languages have positives and negatives and that no one language could be the best". But I believe, given a set of criteria we could compare various programming languages and attempt to figure out which one is better in most criteria. I will attempt to do so in this article.

And to those who may say that "languages don’t matter; only algorithms do" - may I remind you - COBOL is (was?) a programming language.

Just so you know where I am coming from - I am very familiar with C (I have used it to implement x86 kernels) and Perl (I've read and love the Camel) and have studied the following languages - Haskell, Clojure, Go, Rust and Nim. (I'll leave Java and C++ out of the discussion because they make me bitter). I consider myself as a power vim user - I switched to Emacs about 4 years ago after being bitten by the functional bug.

Non criteria

Static vs Dynamic typing

One argument that supports Static typing is that it helps in proving correctness. The argument against it is that one can only prove that the types line up - whether the program is correct from the programmer intention point of view is questionable. Second, it is argued that static types help with refactoring. Again, to the extent of types aligning. Remember

sum = foldr (-) 0

is correct Haskell code - as in it compiles.

The argument for dynamic type system, in my opinion is flawed - they talk about "compiler does not come in the way" etc. - as in, one is allowed to write "incorrect code" and are told about it only at run time.

Anyway, my point is - if you have to shoot for correctness and speed (development and runtime) - shoot for a good design first. The rest will follow.

Design is a somewhat diluted term in the software industry so I'll go with Rich Hickey's definition - which is, I paraphrase here - the art of breaking down a problem such that it can be composed back. Essentially, your implementation must contain tiny modules each of which do one thing. This, will help writing "evident code" that is "obviously correct; instead of, without obvious mistakes"[0]. The type system of the language per se does not help or come in the way of design.

IDE support

I'm just saying that I am not considering that as a parameter for language comparison. If you think that's a grave omission, you should stop reading this article here.

Indentation level as block structure

I can totally get it if you hate the idea. I myself did not like it one bit. It was only after I studied Haskell that I learnt to bear it and later love it.

So I feel - "Don't judge a language by it's choice for block structure"!

Software Transaction memory, CSP style channels

Clojure has demonstrated that these things can be built as a library when your language is powerful enough.

Criteria

Higher order function / Function as first class value

Lambda calculus is "Turing Complete" and it contains nothing more than function definition and function application. There are plenty of articles on the internet that demonstrate how, using just the capability of function definition and function application, one could build all the computing constructs - starting from numerals, booleans etc.

Even in "Why function programming matters", John Hughes demonstrated how vital higher order functions are. Of course, he also said that lazy evaluation is vital - I disagree there since one can build "lazy evaluation" once equipped with higher order functions [2].

Therefore, a programming language that has first class functions is more powerful than a programming language that does not have it.

Almost all modern languages (new versions of old languages) support hugher order functions in some form or other.

Macro support

If the word macro evokes "C macro" / "conditional compilation" in your mind, your probably also believe macros are bad. On the other hand, folks from LSIP side believe that macros give them that extra power (super power of programs that write programs [4]).

Therefore, a programming language that does not have a "powerful macro" (access to AST at compile time) support is inferior.

Languages (that I know of) that support macros are - Lisp/Scheme, Clojure, Rust, Nim,

Strict (Applicative order) evaluation

According to "Why Functional Programming Matters" - Lazy evaluation is one of the two key features that is necessary for a language to facilitate modularity. The other feature being higher order functions. Two points to keep in mind here

Lazy evaluation can be implemented in strict languages - http://matt.might.net/articles/implementing-laziness/
Laziness mixed with IO is unpleasant (to put it very mildly)

So I conclude that a language that has Laziness by default and a tedious way to do/reason about IO is undesirable.

The only "mainstream" language that has lazy evaluation by default and unreasonable (as in hard to reason about) IO is Haskell.

Reach

These days I almost always have to deal with Mac, Linux and Windows and switch between them. On top of that I play with Raspberry-pi. So if I have to invest "10,000 hours" I'd like to it to be in a language that I can use across all machines (of today and tomorrow).

A language that limits my reach is inferior to the one that does not.

Only C and Nim are the good languages in this category.

Ability to target machine code

It is a good idea to program an abstract machine, instead of a real machine. However, not at the cost of never being able to program a specific machine for it's cool features - or having to jump through hoops to do it.

Generating native binaries also make it easier to use it with other systems. Almost all languages (that don’t generate native code) provide a mechanism to load shared libraries (DLL's) and invoke functions.

Now, you may say that, so long as your job gets done, it does not really matter if the actual machine code is executed vs iterpreted by another layer of software. Also, you may argue that virtual machines provide additional opportunities for optimization. I don't agree with either.

First of all, I'd like to waste as little cycles as possible. Now, battery life etc are legitimate reasons for it but I argue that it is actually the essence of using computers - improving efficiency. So, it does matter to me if I am not using optimum memory and CPU cycles. I mean, if you use up more than required resources in "getting your job", the remaining resources will limit what more can be achieved.

About optimization opportunity - yes, it is possible to demonstrate some kind of runtime optimization that may not be possible on today's hardware - but that can never be something that cannot be fixed in the next version of the processor/compiler.

So, if your compiler does not emit native code, it's inferior to the one that does.

Haskell, C, OCaml, Rust, Go and Nim are the good languages in this category.

Memory management / Garbage collection

Garbage collection are of two kinds [5] - tracing and non-tracing. The tracing variety is the most common and it involves keeping track of which objects are "reachable" from root. This introduces a fair amount of non-determinism in the runtime of the program. Typically, the languages that have tracing garbage collector do not give direct access to memory. So, if a language uses a tracing garbage collector and does not give you a mechanism to handle memory directly then it's inferior to the ones that give you direct access to memory and either don’t have garbage collection or use a non-tracing garbage collection.

C, Rust and Nim are the good languages in this category.

Summary

Based on the criteria that I came up with, Nim is a clear winner :)

References

[0] Simon Peyton Jones talks
[1] http://matt.might.net/articles/implementing-laziness
[2] http://www.cs.kent.ac.uk/people/staff/dat/miranda /whyfp90.pdf
[4] http://www.paulgraham.com/avg.html
[5] http://en.wikipedia.org/wiki/Garbage_collection_%28computer_science%29

A little more ignorant each day ...

Tuesday, February 24, 2015

Nim is the best programming language!