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Whitespace

A whitespace compiler for R

1.1 About the language

Whitespace is an imperative, stack based esoteric regular programming language. It only allows three symbols: [Space](" ","S"), [Tab]("\t","T") and [Newline]("\n","L"), which makes the source code invisible.

1.2 Syntax

The full documentation can be found here: http://compsoc.dur.ac.uk/whitespace/tutorial.html, but here is a general breakdown:

[Instruction Modification Parameter][Command][Parameter ended by L]

1.2.1 Instruction Modification parameter

• Space : Stack Manipulation

  1.2.2 Stack Commands

  • Space number : Push the number onto the stack
  • Newline Space : Duplicate the top item on the stack
  • Newline Tab : Swap the top two items on the stack
  • Newline Newline : Delete the top item on the stack
• Tab Space : Arithmetic

  1.2.3 Arithmetic Commands

  • Space Space : +: Second element from top of stack + First element on top of stack
  • Space Tab : -: Second element from top of stack - First element on top of stack
  • Space Newline : *: Second element from top of stack * First element on top of stack
  • Tab Space : /: Second element from top of stack / First element on top of stack
  • Tab Tab : %: Second element from top of stack mod First element on top of stack
• Tab Tab : Heap access

  1.2.3 Heap Commands

  • Space : Put element in heap: second from top of stack: address, first on top of stack: value
  • Tab : Get element from heap and put on stack: first element on top of stack: address
• Newline : Flow Control

  1.2.3 Flow Commands

  • Space Space label : Mark current location with label
  • Space Tab label : Call subrouting at label
  • Space Newline label : Jump unconditionally to label
  • Tab Space label : Jump to label if first item on top of stack == 0
  • Tab Tab label : Jump to label if first item on top of stack < 0
  • Tab Newline : Return subroutine to main code
  • Newline Newline : End program
• Tab Newline : Input/Output

  1.2.3 I/O Commands

  • Space Space : Print character on top of stack
  • Space Tab : Print number on top of stack
  • Tab Space : Read character and store it in label specified by top of stack
  • Tab Tab : Read number and store it in label specified by top of stack

Here is a nicer and more intuitive representation:

1.3 Installation

Simply do:

install.packages("devtools")
library(devtools)
install_github("artificialbreeze/whitespace")

1.4 Use

Create a DFA (Deterministic Finite-State automaton) with code=your code argument:

dfa1=dfa("   \t\t\t\t\t\t\n\t\n  \n\n\n")

Now, parse the syntax:

dfa1.parsed=parse(dfa1)

Finally, compile and run the example:

dfa1.compiled=compile(dfa1.parse)

The above code should output:

# Program output:  ?
# Program stop