The Linda Programming Language

Years ago when I was a university professor, I remember talking about the Linda programming language for a few minutes in a graduate computer science class. What is Linda and what happened to it?

First, Linda isn’t really a standalone programming language. Linda is a set of concepts for parallel programming. Linda has only six keywords: out, eval, in, rd, inp, rdp. Linda is designed to be used in conjunction with a regular programming language such as C, Java, or Python. So it’s usual to talk about things such as Linda-C, Linda-Java, and so on.

The Wikipedia article on Linda is quite good so I won’t repeat its content. Here’s a Hello World program using Linda-C:

/* hello_linda.c */
#include 
#include "linda_lib.h"

void sayHello(int n)
{
  int j;
  in("count", ?j);
  out("count", j+1);
  printf("hello from process %d, count %d\n", n, j);
}

void real_main()
{
  int i;
  out("count", 0);
  for (i = 1; i <= 4; ++i)
    eval("worker", hello_world(i));
  in("count", 4);
  printf("all processes done. \n");
}

The key idea here is that Linda is a programming language extension for parallel programming.

Linda uses tuples. A tuple is essentially a list of pointers/references. And Linda operates in a virtual environment which is often called a TupleSpace. Therefore, Linda languages are sometimes named like JavaSpace, PythonSpace, and so on.

Linda is not an acronym. It’s named after a woman named Linda Lovelace. When Linda was being invented, the Ada programming language was new and the topic of much interest in computer science. Ada was named after Ada Lovelace, a woman who was an assistant to Charles Babbage. Ada is often incorrectly identified as having written the first sort-of computer program for Babbage’s hypothetical computer. Babbage actually wrote the sort-of program in his notes a couple of years before, but didn’t publish it publicly. Anyway, the inventors of Linda named it after Linda Lovelace, a movie star who was the subject of much interest at the time.

So, why didn’t Linda catch on? I don’t know for sure. I suspect that because parallel programming isn’t really used very often, the overhead involved in using Linda just isn’t worth the extra effort required.

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Left: Ada Lovelace (1815 – 1852), namesake of the Ada programming language. Center: Linda Lovelace (1949 – 2002), namesake of the Linda language. Right: Blaise Pascal (1623 – 1662), namesake of the Pascal programming language. Women programmers owe a debt of gratitude to Lovelace. The deep techniques she demonstrated continue to inspire women today.