Abstract data types vs Data structures

C++ data structures is another course am learning this semester. This course is a pre-requisite for all non-Computer Science students. I have already learnt and implemented all the C++ data structures in a private course during my undergraduate studies, but not with the same understanding am learning them these days. Frankly I dont know much about data structures during my work experience. So I consider this course as an opportunity to get my hands on C++ again and implement various datastructures.

First thing I got to know is.. the difference between the abstract data types (ADT) and datastructures. Earlier I thought they are same.

Before starting that, we need to be clear about the logical and implementation level of data. Let us take an example of a simple built-in data type integer. At the logic level, we application programmers know only about what are the operations an integer data type can perform, ie., addition, subtraction etc., But we are no way aware of how the data type is actually implemented. At the implementation level, it is about how the data type integer is implemented in the machine level, ie., it could either of binary-coded decimal, unsigned binary, sign-and-magnitude binary, One's complement and Two's complement notation.

Now.. for the understanding the ADT and data structure, we need to assume a higher level abstraction where we have the built-in types at the implementation level.

To put it simple, ADT is a logical description and data structure is concrete. ADT is the logical picture of the data and the operations to manipulate the component elements of the data. Data structure is the actual representation of the data during the implementation and the algorithms to manipulate the data elements. ADT is in the logical level and data structure is in the implementation level.

As you can see, ADT is implementation independent. For example, it only describes what a data type List consists (data) and what are the operations it can perform, but it has no information about how the List is actually implemented.

Whereas data structure is implementation dependent, as in the same example, it is about how the List implemented ie., using array or linked list. Ultimately, data structure is how we implement the data in an abstract data type.

This is something new of what I have learnt.

got to know.. 'Leda'

I just came across a new programming language called Leda when I was reading the book 'Thinking in C++' by Bruce Eckel. What is so unique about Leda is, it is a multiparadigm programming language. Multiparadigm, I mean, has all the paradigms of programming languages implemented in it ie., imperative, object-oriented, functional and logic!

As we all know that these abtraction of programming languages were basically to address the problem needs to be solved by the computer. As in imperative languages the problem space and solution space were different, so it became tedious for a programmer to map the spaces with each other. And then came the better abstraction, object-oriented programming. Here the problem space and solution space looked similar! like.. all were treated as objects ie., the abstraction was catered in a way that it fits the real world. Later we had functional and logic paradigms which had their own conceptualization of the real world ie., as 'lists' in LISP and 'algorithms' in Prolog. So there came a point that every paradigm best suits only for the particular kind of problem that it was catered for.

So Leda was designed to have all the paradigms in one language and the programmer can chose the paradigm based on which will best suit his problem to be solved. It was founded by Timothy Budd. There is a book named 'Multiparadigm Programming in Leda' authored by the founder himself. I tried finding a free soft copy of this book to learn more but in vain. But I got a research paper on this topic from my univ's 'Adaptive Systems and Languages group'. Will post more when I get time to read that paper.