The Whitespace programming language gained some notoriety when a Slashdot article mentioned it on 1 Apr 2003. I wanted to revisit the language to celebrate the 21st birthday of its fame.

You will need a whitespace interpreter. The original is still available online, courtesy of the Wayback Machine, but it needs a couple of source tweaks to work with modern Haskell compilers. There's a patch file at WSpace.patch; if you've downloaded and unpacked v0.3, so you have WSpace in your current directory, patch it with patch -p0 < WSpace.patch; you should then be able to cd WSpace; make.

Alternatively, there's a long list of interpreters at https://github.com/wspace/corpus, many of which are written in languages that you'll likely already have installed on your machine. However, many of the interpreters I looked at were incorrect in various ways, e.g. getting the order of operands wrong for arithmetic operations; other programs on that list were libraries, but didn't provide a command-line interface. https://github.com/kraterkraken/Whitespace provides a main() that takes the name of a file to run.

The file apr1.ws is, effectively, a "Hello world". However, the obvious way of writing a hello world in Whitespace is to push 72 (H) onto the stack, print the character with the ASCII code at the top of stack, then push 101 (e), print it, etc. This is what the Wikipedia example does. The code here uses more of the language features (addition, subtraction, multiplication, modulo, storing/retrieving from the heap, and looping), and (I assert) is more interesting as a result.

The file apr1.c is that same Whitespace source but also a valid C program that implements approximately the same operations to print approximately the same message.