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15 January 2011

Importance of Expressiveness in Programming Languages

It is a while i had a post here and in fact this is my first post in 2011. I happy to have my first post of the year on the topic that is of huge interest to me these days.

Why aren't we still programming in assembly languages? The threads, inter-process communication mechanisms can be done in assembly language but not easily though. With assembly language, there is only level of abstraction - ability to see the requirements as sequence of bits that are comprehensible by the machine. When you want make your program to run in another target platform, you may need to change both the abstraction and implementation. The assembly language is not as expressive as procedural language. In order to increment a number, you have locate the address, move it to accumulator, add it by one and store back to the same memory location. There is no clear division of responsibility. You have more number of steps to do in assembly but that is very primitive in procedural language.

Why aren't we writing program with procedural language alone? Procedural language is less expressive than object oriented program. The amount of code that a developer should write to accomplish a logic is more in the case of procedural language. While the level of abstraction is moved a level up from the bare machine, still the abstraction is not efficient to solve a problem in application domain. As far as the application is concerned (and in imperative languages), a task is accomplished with side effects. You call a method and it changes the state of few objects. The data and operation have to cohesive. So, in application development it is highly essential that we glue the data together with operations because these operations are specialized over the data.

There are other types of programming languages like functional programming inspired by lambda calculus and one can write their own language for a particular domain. There is one basic commonality in all types of programming languages - they try to be more expressive to make the life of developers easier. For example, today many developers are thinking about writing concurrent programs not only due to multi-cores being prevalent but also due to modern languages that made multi-threading highly expressive. It is easier to write multi-threaded in Java than in C or assembly.

As we move on, we will see many more expressive language, expressive than Java world and it is part of evolution of programming languages.

The article was written after reading Grady Booch's "OOAD with Application" and first chapter of "Programming Paradigms". Hoping to bring few posts on the subject this year. Watch out this space.