Cholc

Cholc is an esoteric programming language made up of sequences of musical chords.

Examples

Hello world

A A A A A A A A A
|: F G E Am :|
F Fm
|: C C C C C C C C A A A B Em :|
C Cm X
|: Db Eb Eb Eb Eb Eb C C C Fm :|
C C X
|: C C#m :|
Cm Cm X X
C C C X
Ebm X
D Dm
A A A A A X
|: F G Cm :|
Gm X
F Fm X
F F F X
Gm Gm 
D F# Bm |: Gm D F# Bm :|
Gm X
|: Gm Dm :|
G X
A X

output:

Hello, world!

Count up from 1 to 30

F F F F F F F F |: C C C C C C Fm :|
Dm Dm Dm Dm Dm Dm Dm Dm Dm
|: Ab Bb G Cm :|
Am Am Am |: |: G Gm X F Bb X D :| G X |: Bbm Dm Fm :| Bb Bbm X A :|

output:

010203040506070809101112131415161718192021222324252627282930

Specification

Operators

Operators in Cholc are similar to Brainfuck. They move a pointer, and increment/decrement its value.

Operator	Role
{major chord}	increment the value referred by the pointer
{minor chord}	decrement the value referred by the pointer
|:	jump right after to the corresponding :| if the value referred by the pointer is 0
:|	jump right after to the corresponding |: if the value referred by the pointer is not 0
v	read 1 byte from an input and write to the pointer
X	write the value referred by the pointer to an output

Only triad major/minor chords can be used as operators. Other chords such as 7th or sus4 cannot be used. A hash # and an alphabet b is used as a sharp and flat symbol respectively. Here is an example of chord operations.

C
Cm
F#
Bbm
// Any enharmonic equivalents can be used
A#m

Moving pointer

Moving pointer in Cholc is defined by chord progressions. The movement of the pointer depends on the interval between the two chords in a row.

Progression	Interval	Example	Pointer movement
weak progression	7 semitones (perfect 5th)	C G	1
strong progression	5 semitones (perfect 4th)	G C	-1

Any pair of chords moves the pointer and its movement is "how many times to add perfect fifth".

Here are the rules of the movement.

• major/minor does not affect to the pointer movement
• if movement > 5, subtract 12 (treated as negative movement)

Example:

Chords	Pointer movement
C C	0
C G	+1
C D	+2
C B	+5
C Gb	-6
C F	-1
F Bb	-1
F G	+2
C Fm	-1
C Cm	0

Order of pointer movement

The pointer movement occurs between two chord operations.

For example, C G is evaluated in this order.

At first, all memory is filled with 0 and the pointer refers address 0.

Address	0	1
pointer	here
value	0	0

Chord C is evaluated and the value is incremented.

Address	0	1
pointer	here
value	1	0

Chord progression C G is evaluated and the pointer is moved to address 1.

Address	0	1
pointer		here
value	1	0

Finally chord G is evaluated and the value is incremented.

Address	0	1
pointer		here
value	1	1

Turing completeness

Cholc is turing complete. Any Brainfuck source code can be converted to a Cholc source code by the covertion table below.

Brainfuck	Cholc
+	C
-	Cm
>	C Cm E Em Ab Abm C Cm
<	C Cm Ab Abm E Em C Cm
[	|:
]	:|
,	v
.	X

External resources

• Implementation: an implementation and online playground written in TypeScript
• Playground: an online playground where the sound of the chord can be played during the evaluation