This is the archived website of SI 413 from the Fall 2012 semester. Feel free to browse around; you may also find more recent offerings at my teaching page.

J was designed in 1990 by Iverson and Hui. This is direct descendant of APL (A Programming Language), which uses a paradigm called array programming in which every operation is applied by default in parallel to an entire array of data. These languages are usually very terse and well-suited to mathematical and financial applications.

Useful Links

Jsoftware, the official home of the language and interpreter.
Wikipedia page
J primer. Decent introductory guide to the language.
99 bottles of beer program.

Installing the interpreter

The J interpreter, version 602, is installed for you on the CS Linux environment. This is also available for other platforms, from this page. I will use the jconsole command to test your code, but you are encouraged to use the GUI, jwd, for development.

How I will run your code

You should create an argument-free function main to run your program at the top level. Save your program in a file called proj.ijs.

I will test your code in the same environment as the lab machines in MI 302, using the command

  echo "main" | jconsole proj.ijs

So for example, the 99 bottles of beer program, for my purposes, would be written as

bob =: ": , ' bottles of beer'"_ -. 1&= # 's'"_
bobw=: bob , ' on the wall'"_
beer=: bobw , ', '"_ , bob , '; take one down and pass it around, '"_ , bobw@<:
main=: beer"0 (- i.) 99