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BlueSpace

BlueSpace is an interpreter for the Whitespace programming language.

Whitespace

Whitespace is an esoteric programming language that was created by Edwin Brady and Chris Morris and is based at http://compsoc.dur.ac.uk/whitespace/ (archived version from 2015-07-15). Its syntax consists entirely of invisible characters: space, tab and line feed.

BlueSpace

This interpreter is written in Python 3 and boasts the following features:

  • Interpret Whitespace code
  • Compile Whitespace code to Python and optionally execute it
    • Optimise the generated Python code
  • Accept and translate between Whitespace syntax, as well as:
    • A printable syntax, which substitutes space, tab and linefeed with s, t and n, respectively
    • An assembly-style syntax (described below)

To run a Whitespace program, simply execute ./bspace.py source.ws; to see other options, use ./bspace.py --help.

Assembly Syntax

Each line of the source must match one of the following forms, where number is any decimal integer and label is any string of s and t characters with an optional trailing n. Each line maps to a single Whitespace instruction. A # begins a comment; it and any subsequent characters on the same line are ignored.

Push number
Duplicate
Copy number
Swap
Discard
Slide number

Add
Subtract
Multiply
Divide
Modulo

Store
Retrieve

Label label
Call label
Jump label
JumpZero label
JumpNegative label
Return
End

OutputChar
OutputNum
ReadChar
ReadNum

Compatibility

Known incompatibilities between BlueSpace 1.1 and WSpace 0.3:

  • The ReadNumber instruction (tab-linefeed-tab-tab): WSpace accepts spaces between the negative sign and the number (e.g. - 123 is accepted as equivalent to -123) which BlueSpace does not. Conversely, BlueSpace accepts a leading plus. (e.g. +12 is equivalent to 12) which is rejected by WSpace.
  • WSpace ignores all trailling characters after the last point in the code that is visited; BlueSpace requires the entire input to be a valid Whitespace program. For example, the program consisting of four linefeeds is the null program according to WSpace, but BlueSpace reports a syntax error since the fourth linefeed does not constitute a valid command. This is due to WSpace's lazy parsing semantics.
  • If a program defines the same label more than once, WSpace jumps to the first instance, while BlueSpace jumps to the last. I consider such a program to be erroneous and later versions of BlueSpace may report this as such.

Programs

Here is some code I've written in Whitespace.

  • Here's the classic 99 Bottles of Beer program. It's encoded in the printable syntax, so it must be run with ./bspace.py -iprintable. (I nearly always write code in the printable syntax, as it is much easier to read.)
  • Here's my shortest quine to date, weighing in at a mere 486 bytes. While we're at it, here's the disassembly (although, of course, it is not a quine in this form).
  • The above has been improved to 406 bytes. Here's the Whitespace and the disassembly.

Name

Why BlueSpace? It is, in fact, named after Sir Lancelot's favourite colour; anyone who is familiar with the Python documentation should be sufficiently conditioned to expect such silliness.

More

I have another page about Whitespace and BlueSpace which includes some of my own Whitespace programs at http://cpjsmith.co.uk/whitespace