Java, Python, Scripting

Sun recruits Jython leads

I know this isn’t exactly breaking news but it is further evidence that Sun is aiming to turn the JVM in a language agnostic platform. It’s also good news for the Jython project which has suffered a long period of hibernation and which has fallen far behind CPython in terms of its compatibility.

I like Python as a language and its clarity is great for one time scripts (which never really are). I would really like it to be a full member of the JVM-compatibles.

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Groovy, Java, Python, Ruby, Scripting

Groovy or JRuby?

Martin Fowler blogged about the question a couple of days ago and ever since I have pondering that maybe it is not really the right question to ask.

I currently toodle between Jython, JRuby and Groovy for various reasons and I am an expert in none. The interesting thing I have found is that it is hard to pick one and just focus on that. To some extent they overlap heavily: they are all cross-platfrom, they are all dynamic, they all integrate with Java API stack I’ve committed to memory.

The first thing to say is that I am interested in scripting languages for prototyping and admin style scripting. I have never used Rails and the Grails data-model means that you need a specific kind of project to work on. If you want to use a particular product and that is only on one platform then that kind of makes your decision for you.

Each language has its own strengths, from my point of view I would categorise them in the following way. Jython has Python’s readability and solid language design, JRuby has Sun’s support, excellent community contributed library code and is very dynamic, Groovy is mini-Java, so it’s easy to learn and most importantly it has a functioning interactive console.

The last point might seem a bit weird, what about jirb and jython‘s interactive mode? Well Martin makes a very important point in his post about the purpose of these ports. Both JRuby and Jython aim to stay faithful to their source languages and be able to run code from their parent C implementations while expanding the API by accessing the Java libraries. Groovy on the other hand stays close to Java syntax and is the only one of the three that allows you to cut and paste code from a regular Java application and then play around with it in an interactive session. That is a very powerful and compelling feature.

Almost all the Groovy I do either comes from wanting to leverage or understand a piece of Java code.

All my Jython work on the other hand is about wanting to automate administration or manual tasks in a clear and concise fashion. Python’s dynamic data structures help, but so does zxJDBC the Jython specific database library that mixes DBI with JDBC to create a highly portable but simple database connectivity solution with no boilerplate!

JRuby on the other hand is something that only really comes up because Alpha Geeks love it. The syntax is gnarled and there is a significant learning curve before someone from a Java background can get “The Ruby Way” of things. The new integration of JRuby into NetBeans though makes developing in the language a comparative snap and I would suspect that JRuby will be a valid choice of application development language alongside Java now. The choice will be driven by the problems you are trying to solve not because one language is inherently “better” than the other.

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Python, Scripting

Python Functional Programming

Something that is relatively new to me in Python is the lambda function that allows you to do a bit of functional programming. Today I created a Dictionary of functions and it all Just Worked. It reminded me a bit of C function pointers, Ruby closures and Java anonymous classes but it seemed more logical and natural than all of them.

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Python, Ruby, Scripting

Starting Ruby and Python

This weekend I had a chance to start some Ruby and Python programming. My favourite scripting language to date is Perl and in terms of Java scripting I do actually like Groovy (although it has rapidly fallen out of favour with the Java crowd). Out of the two I have done currently done more complex stuff with Ruby but one thing is pretty immediate and that is that Python is very much on the back foot when it come to OOP scripting.

That’s not necessarily a bad thing though as actually scripting tends to be procedural and my Python script seemed to do a similar amount of work without the involvement of OO code. If I wanted something done quickly I would probably go for Python in the same way I go for Perl now. However if I thought something had legs and needed to be supported and expanded I would definitely go with Ruby.

One thing that both languages seem to have issues with is their big libraries. Most of my time with both languages was spent looking up how to perform some action. I was certain that neither of the languages required me to roll my own but I felt the situation was a lot like C and C++. C, like Perl, has the advantage of being syntactically very compact. You have to learn very little to know the language completely. Of course that means it lacks a certain power that comes from building on the capabilities of the language.

Perl answers this problem with modules which are a good idea as you only have to learn about standard libraries in little module sized chunks that match the problem you’re working on.

Python is kind of similar, in the sense there isn’t a lot in the core, but different in that, like C++ (and Java), you need to know your standard library if you are really going to get stuff done effectively.

Ruby is an altogether different beast. To get anything done you have to grapple with what feels, from my Java-centric point of view, like a very arbitrary API that is attached to every object. If you know the capabilities of a type then you have access to a lot of power. If you don’t, then you are swearing, scratching your head and reaching for the API description in the Pickaxe book.

One key thing that I feel is holding me back is the lack of variable typing. Having dynamically typed variables is cool, unless of course I know that I only want one type of variable (say an Integer). Maybe the code reflection and auto-completion features of Java are influencing me here but I do think it is helpful to be able to specify a type for a variable and then have the programmer’s editor or IDE be able to determine the API available to you.

Oh and yes, I might be making this complaint because I have already been caught out by the lack of automatic conversion between strings and numbers.

Overall my opinion at the moment is that Python is like Perl only cleaner and more legible. I think it would be really good for protoyping an application with a big team because there is a lot more consistency in the syntax and the style.

However Ruby’s object-orientation does mean that it would be an obvious choice for trying out OO Java ideas. Particularly if something like JRuby helped bring the benefits of both languages together (as well as making the most of my heavy investment in memorising huge chunks of the Java API).

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