Choon

A translator from C++ to the esoteric programming language Choon, based musical notation for syntax.

Choon Instruction Set

Full Set

Symbol	Name	Purpose
[A-G]	Notes	Numbers
+	Up	Transpose up
-	Down	Transpose down
.	Cancel	Reset transpose
[a-z]	Markers	Variables
=	Play from output	Reference
%	John Cage	No-op
||::||	Repeat Bars	Loop
~	Tuning Fork	Break

Note Values

There are 12 notes in the western musical scale, and they are notated like this:

Choon Instruction	Value
G	-5
G#	-4
A	-3
A#	-2
B	-1
C	0
C#	1
D	2
D#	3
E	4
F	5
F#	6

Transpositions

Symbol	Name	Description
+	up	Transposes (Increases) all subsequent notes played by the amount of the last note played
-	down	Transposes (Decreases) all subsequent notes played by the amount of the last note played
.	cancel	Sets the transposition back to 0

Transpositions are cumulative, so the Choon code D+ transposes all future notes up by 2 and D++ by 4.

Also, the value used for transposition is the last value played which includes any exisiting transposition. Hence the code D+D+ transposes future notes by 6 and not 4.

Markers

A marker is a lower case letter/word that remembers a point in the output stream. Referring to a marker (see below) will cause the note played just after the Marker to be played again. Note that transpositions will affect this newly played note.

Play From Output

The Play From Output instruction = allows you to play notes that have already been played in the output stream.

Reference Type	Example	Result
Absolute	=3	Plays the 3rd note played since the program began
Relative	=-3	Plays the 3rd most recent note played
Marker	=x	Plays the note played just after the marker x

It is common to immediately re-use a marker for eg: x =x. This is equivalent to saying x=x+y in a conventional language (where y is the current transpose value).

John Cage

The John Cage instruction % causes a one note silence in the output stream. The transposition value of a John Cage is zero - '%-' and '%+' are no-ops (except that a single silence is added to the output).

Repeat Bars

Repeat Bars (||: and :||) create loops. The loop repeats based on the last note played before encountering ||:. Zero or negative values jump to the matching :|| to start playing from there.

John Cage indicates an infinite loop: %||: :|| creates an infinite loop.

Sample Programs

C++ Code	Choon Code	Music Played
int a=1,b=2; a+=b; cout<<a;	. C# + a C . D + b C . =b + a =a. =a + C	Listen
int a; a=20*30; cout<<a;	. t0 C F#+D#+C + C ||: . F+C+C + t0 =t0 :|| . F#+D#+C + C - - C ||: . F+C+C - t0 =t0 :||. =t0 + a C . =a + C	Listen
int a=0,i; for(i=0;i<10;i++){ a+=i; } cout<<a;	. C + a C . C + i C % ||:. F+C + t0 C. =i + C - - t0 =t0. =t0 - C ||: C ~ :|| ~. =i + a =a . =i + i C#:|| . =a + C	Listen
# Fibonacci int a=0,b=1,c,i; for(i=0;i<10;i++){ cout<<a; c=a+b; a=b; b=c; } cout<<a	. C + a C . C# + b C . C + i C % ||:. F+C + t0 C. =i + C - - t0 =t0. =t0 - C ||: C ~ :|| ~ . =a + 0. =a + t1 C . =b + t1 =t1. =t1 + c C . =b + a C . =c + b C . =i + i C#:|| . =a + C	Listen

Acknowledgements

Special thanks to Stephen Stykes, for creating the idea of Choon and providing the reference interpreter in Ruby.