From C# on Mono, to Clojure on the JVM

Posted: May 26th, 2009 | Author: jeswinpk | Filed under: general | 15 Comments »

Last week, we had to take a decision that reminded us of a similar situation we faced three years back. On which platform and language will we develop back-end services?

Going with Mono, in 2006

In early 2006, we were working on a fairly large Social Networking project which included building a few long running processes. We decided to build these in the popular, but not yet widely deployed platform called Mono. Two factors tilted the decision in favor of Mono, the most important being that we were building the application on Linux, and the second being that we had decided to use a mainstream object-oriented, statically-typed language for building these components. That leaves us with Java and C#; while Java was left in the quagmire of community-driven, slow design process, C# was getting increasingly productive leaving Java behind in terms of expressiveness. By 2006, Mono had an excellent C# compiler, an efficient runtime, and good coverage of the .Net Base Class Libraries.

Though the project eventually failed due to non-technical reasons, Mono itself served us well for 3 years. Over that period, Mono improved by leaps and bounds. Compatibility is great with Net 2.0 libraries being almost entirely supported, compilers are exceptional, MonoDevelop 2.0 has become a capable IDE, and performance is comparable to Microsoft .Net itself. In specific benchmarks, the Mono runtime even bests the official  .Net runtime. Often, the mono compiler supports upcoming C# features ahead of the official Microsoft release.

We could say that the “Mono Project” has done well over the years. I actually admire the Mono Team; they have faced unnecessary criticism within the Open Source community, often by people who knew little about the project. That did not stop them from building a great product.

However, my confidence in Mono has been waning for some time.

In the Shadows of .Net

Back in 2006, we put our trust in Mono because we refused, or perhaps disliked, to vilify a project solely because it emulated something created at Microsoft. While Open Source backers generally dislike Microsoft technology, with Mono they had another argument that being a clone it could be affected by a number of patents that Microsoft holds related to the .Net framework. This point often comes up in debates about the “safety” of the Mono project, the defense of Mono being that large parts of the .Net specification are an open, published ECMA standard. I sided with the Mono supporters then, downplaying the risk of patents from Microsoft. But then in November, Microsoft and Novell announced their Patent Agreement, which guarantees patent protection exclusively for users of Novell Linux. The Mono project is largely supported by Novell, and such an agreement is disastrous for a community project like Mono. At this point, the fence-sitters in the Open Source community largely crossed over to the anti-Mono camp. Perhaps, they were justified in doing so. I could no longer defend Mono, and my belief in the framework getting wider acceptance has diminished significantly since then.

One might wonder why acceptance or ideological reasons should affect the platform we choose to build a product on. It just needs to work well, right? It is not that easy. Today my company works with customers on Microsoft and non-Microsoft platforms. We have skills on Microsoft and Open Source technologies, and while consulting or providing services to our customers we choose the right tool for the job irrespective of our ideological leaning. But when building our own products, we  are convinced about the advantages of Open Source. And as a company, we see Open Source as a principle and ideology – not just for its commercial benefit. Building a new product requires a lot of sacrifice, stamina, coffee and redbull. And you will only build it on a technology you believe in.

There are other minor issues that make Mono a stranger in Open Source land. Mono uses very Windows specific conventions, like “.exe” for executables and “.dll” for libraries. For non-windows users some of these conventions look odd. Again, this is not Mono’s fault; rather a consequence of emulating a platform designed for a very different Operating System.

It is entirely possible that Mono can suddenly gain acceptance if Microsoft decides to relinquish patent claims regarding the .Net framework. If it happens, .Net and Mono could well become an powerful challenger to the dominance of Java. This is very unlikely, Microsoft’s current strategy seems to be relying strongly on patents and IP to ward off the looming threat from Linux.

For now, we decided to look beyond Mono and C#.

What about Python?

In the last two years, I have mostly used Python with Django for web development. It is easy to learn and to apply. Documentation is plentiful, and there are libraries for getting most things done. While Python is  easy and practical, there was nothing quite remarkable about it. I felt Python’s strengths were not a consequence of well thought-out language design; instead it was the flexibility inherent in the dynamic nature of the language.

The language itself seems to be going backwards. I do not deny that I have an affection for functional-style programming, but its relevance cannot be overlooked anymore. In a variety of situations, Functional Programming (FP) is more concise, and it is also more suited for the dawning Parallel Programming era. For this reason alone, languages like C# are incorporating functional concepts in future versions. But not Guido;  Python’s benevolent dictator has a well known dislike for functional style programming. Guido deserves credit for creating a very popular programming language, but you wonder if he is paying attention to the evolution of contemporary programming languages.

Some people say that Python’s legacy will be like that of Visual Basic; if it ever gets that popular. I doubt whether it will be as popular as “VeeBee”, but I don’t disagree. There are more capable languages out there. If we ever accomplish interoperability across dynamic languages, I predict that Python would have a bleak future. Why aren’t the Parrots speaking, yet?

The JVM

Java is the most common language for building applications today; due to its maturity, multi-platform support, proven reliability and the huge-huge ecosystem built around it. But Java itself is a really sucky language. It is boring to write code in Java, and even simple tasks tend to be very lengthy. Steve Yegge’s ‘Kingdom of Nouns‘ captures this verbosity in a humorous style.

The JVM is however, quite an interesting platform.  While originally designed for the Java language, it is now the target of many new languages. Some of these languages have been around for some time now and have gained some momentum, like Scala, JRuby, Groovy and Clojure. Groovy has not caught on as much as the others; so it fails my “excellent community” criteria. JRuby’s biggest problem is Ruby itself; rockstars are unlikely to use the JVM.

But Scala is impressive; has great interop with Java, has a growing community around it,  and recently acquired a really high-profile user – Twitter. If you have been programming in Java or C#, Scala is a wonderful alternative. For Java developers, Scala offers a leap in productivity and the ability to call and get called by Java code. If you are on the Microsoft stack and hate the JVM because you hate Java, Scala offers the expressiveness that was recently introduced into C#.

But I knew Scala wasn’t what I was looking for. I actually knew what I wanted; I wanted a language with few syntactic rules and constructs. I wanted to move to a language I do not have to discard any time soon.  I wanted something like the ‘Hundred Year Language‘.

LISP will win, eventually

LISP is a bit like our company’s motto: “Simplicity is the ultimate sophistication.” – originally by Leonardo DaVinci. The language itself is so simple that you could learn the semantics in less time than it takes to read this article. This simplicity is achieved by abstracting ideas in programming languages to the extreme; yielding a simple form which is infinitely extensible. This extensibility comes from the ability to treat a program as data, and manipulate the program itself, using a feature called Macros.

While the syntax of LISP is very simple and elegant, writing a typical business or web application in LISP is (or was) much harder; perhaps an order of magnitude harder. This is especially true for newbies; unless they are really determined it is difficult to find documentation and useful libraries. This happened to me as well. I had read many books on LISP, but I did not have the confidence to execute a real project in LISP. It has been done before by so many others, but there is a big challenge in transitioning from a theoretical understanding of LISP and getting it to work in practice.

Although I was unable to use LISP in any production code, what I learnt from LISP profoundly impacted the way I saw programming. And since then, I have been keeping a close watch on upcoming languages bearing any resemblance to LISP. One such language was Clojure.

Clojure, the acceptable LISP

Clojure is a dialect of LISP and a dynamic programming language, running on the JVM.   It has all the benefits of LISP, including the powerful macro system. It also has useful features which help with parallel programming; like Software Transactional Memory for dealing with shared state without worries. Clojure makes some of LISP’s biggest problems go away. Lack of Libraries and other supporting infrastructure like Application Servers. Java has libraries for everything, from connecting to SAP to talking to Twitter. And you could deploy on robust servers like Tomcat.

Everything ever built for Java can be used with Clojure.

Clojure is very young, and like any new programming language you would encounter minor inconsistencies and bugs. But it is stable enough to get work done. There is an active and rapidly growing community around the language now, contributing useful modules and supporting new users. Clojure is like a breath of fresh air.

We are excited about building our new product on Clojure. Such unconventional choices are only possible when you are building your own product; but hey, that’s one good reason to do one. Enthusiasm is  vital ingredient in building products; they sprout from a variety of reasons. Like usefulness, financial rewards, challenges, technology, ..and programming languages like Clojure.

Jeswin P Kumar
(jeswinpk@my-company-name-is-AGILEHEAD.com)

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