I am selfish
| Paradigm(s) | imperative |
|---|---|
| Designed by | User:Ttulka |
| Appeared in | 2024 |
| Dimensions | one-dimensional |
| Computational class | Turing complete |
| Major implementations | Interpreter in JavaScript |
| File extension(s) | .i |
I am selfish is an esoteric programming language that solely discusses itself, permitting only variations of the symbol "I":
| Symbol | Encoded | Unicode name |
|---|---|---|
I |
\u0049 | Latin capital letter I |
Ι |
\u0399 | Greek capital letter iota |
І |
\u0406 | Cyrillic capital letter Byelorussian-Ukrainian I |
Ӏ |
\u04c0 | Cyrillic letter Palochka |
Language
Based on the symbols they are denoted by, instructions operate on one of four registers:
| Symbol | Encoded | Register |
|---|---|---|
I |
\u0049 | 0 |
Ι |
\u0399 | 1 |
І |
\u0406 | 2 |
Ӏ |
\u04c0 | 3 |
I am selfish has four instructions: increment, decrement, selection, and jump. Instructions are denoted as a unary number using one of the "I" symbols:
| Number | Instruction | Meaning | Example |
|---|---|---|---|
| 1 | Increment | Increments the register | I
|
| 2 | Decrement | Decrements the register | II
|
| 3 | Selection | Skips the next instruction if the register is zero | III
|
| ≥4 | Jump | Jumps to an instruction | IIII, IIIII, IIIIII
|
Jump is unconditional; its target is determined by the number of symbols appended to the instruction. Four symbols refer to zero, five to one, six to two, and so on. It counts only instructions that use the same symbols as the jump itself.
Since only "I" symbols are allowed, instructions with different symbols must be used as separators; otherwise, the code would be ambiguous.
The selection and jump instructions together provide conditional jumps sufficient for Turing completeness.
Examples
(Newlines are added arbitrarily.)
Infinite loop
Never stops:
IIII
Addition
Add A and B (A = A + B):
ΙΙΙІІІІІΙΙIΙΙΙΙІІ
Multiplication
Multiples A with B (A = A × B):
IIIΙΙΙΙΙIIІIIIIΙΙΙІІІІІІІІІІΙΙІІІӀӀӀӀӀӀІІIӀІІІІІІӀӀӀΙΙΙΙΙӀӀІӀӀӀӀӀӀІІ
Fibonacci sequence
Computes the Fibonacci sequence starting with the elements in A and B, continuing until the number of elements specified in C:
ІІІӀӀӀӀӀӀӀӀӀӀІІΙΙΙIIIIIΙΙӀΙΙΙΙIIIӀӀӀӀӀӀӀIIΙIIIIIӀӀӀІІІІӀӀIΙӀӀӀӀӀӀІІӀӀ
Hello World
For computing "Hello World" the numbers in the registers must be interpreted as letters. It can achieved by defining a simple alphabet:
| Letter | Value |
|---|---|
⎵ |
1 |
d |
2 |
e |
3 |
H |
4 |
l |
5 |
o |
6 |
r |
7 |
W |
8 |
The following program sets A progressively to 4, 3, 5, 5, 6, 1, 8, 6, 7, 5, 2 which corresponds to "Hello World":
IΙΙIΙΙIΙΙIΙΙIIΙΙIIΙΙIIΙΙIIΙΙIΙΙIΙΙIΙΙIIΙΙIIΙΙIIΙΙIΙΙIΙΙIΙΙIΙΙ IΙΙIIΙΙIIΙΙIIΙΙIIΙΙIIΙΙIΙΙIΙΙIΙΙIΙΙIΙΙIIΙΙIIΙΙIIΙΙIIΙΙIIΙΙIΙΙ IΙΙIΙΙIΙΙIΙΙIΙΙIIΙΙIIΙΙIIΙΙIIΙΙIIΙΙIIΙΙIΙΙIIΙΙIΙΙIΙΙIΙΙIΙΙIΙΙ IΙΙIΙΙIΙΙIIΙΙIIΙΙIIΙΙIIΙΙIIΙΙIIΙΙIIΙΙIIΙΙIΙΙIΙΙIΙΙIΙΙIΙΙIΙΙII ΙΙIIΙΙIIΙΙIIΙΙIIΙΙIIΙΙIΙΙIΙΙIΙΙIΙΙIΙΙIΙΙIΙΙIIΙΙIIΙΙIIΙΙIIΙΙII ΙΙIIΙΙIIΙΙIΙΙIΙΙIΙΙIΙΙIΙΙIIΙΙIIΙΙIIΙΙIIΙΙIIΙΙIΙΙIΙΙIIΙΙII