Ichi

Ichi means 'one' in Japanese. Ichi is a one-instruction Turing-complete esoteric programming language created by User:TheCanon2.

Ichi was designed to be a Turing-complete language with even fewer operands than Divmeq. However, Ichi has flaws that make Divmeq better for demonstrating Turing-completeness.

• Negative integers
• Complex arithmetic
• Output

Commands

Ichi has two unbounded registers with addresses 0 and 1. The Ichi command accepts only one operand, x.

Change register with address x modulo 2 by the sign of x. If said register is -1, move 1 line forward. Else, goto line absolute of x divided by 2 rounded down.

However, there are three exceptions.

If x is 0 or 1, print the value of register x and unconditionally move 1 line forward.

If x is -1, clear the registers, accept two numeric inputs to be written to the two registers, then unconditionally move 1 line forward.

The latter is an instruction baked in to every Ichi program.

Line numbers start at 1 and increment by 1 for each line in the program. The program halts if the line number is greater than the length of the program.

Examples

Hello, World!

5 7 9 11 13 15 17 19 -23 40 24 26 28 30 32 34 36 38 18 -42 0
47 49 51 53 -57 76 58 60 62 64 66 68 70 72 74 52 -78 -80 0
84 86 88 90 92 94 96 0 0 102 104 106 0
111 113 115 117 119 121 123 125 127 -131 -146 -132 -134 -136 -138 -140 -142 -144 -126 -148
-150 0 -154 -156 -158 -160 -162 -164 -166 -168 -170 -172 -174 -176 0
181 183 185 187 189 191 193 195 197 199 -203 214 204 206 208 210 212 198 0
219 221 223 225 227 229 231 -235 242 236 238 240 230 -244 0 248 250 252 0
-256 -258 -260 -262 -264 -266 0 -270 -272 -274 -276 -278 -280 -282 -284 0
289 291 293 295 297 299 301 303 305 -309 -324 -310 -312 -314 -316 -318 -320 -322 -304
-326 -328 0

Prints the ASCII values of the characters in 'Hello, World!' since Ichi has no character output.

Quine

0

This is the smallest in a set of infinitely many Ichi quines with all-zero instructions.

Truth machine

-10 6 0 16 12 0 -10

Two-Time Cat

0 1

XKCD Random Number

4 6 8 10 0

A+B problem

4 -3 -8 0

A-B problem

-4 -3 8 0

Print all natural numbers

0 2

Computational class

Ichi is Turing-complete for it can simulate a two-register Minsky machine.

4 Increment register 0

-6 8 0 Decrement register 0 and jump to instruction 3 unless it is zero in which jump to instruction 4.

Implementations

The following Python script is an interpreter.

prgm = input('>Ichi ')
prgm = list(prgm.split(" "))
for i in range(0, len(prgm)):
    prgm[i] = int(prgm[i])
prgm.insert(0, -1)
# Initialises registers
cells = [0, 0]
# Executes program
inst = 0
def ichi(x):
    global prgm
    global cells
    global inst
    if x == -1:
        cells = [0, 0]
        init = input('>i ')
        if len(init) != 0:
            init = list(init.split(" "))
        if len(init) > 0:
            cells[0] = int(init[0])
        if len(init) > 1:
            cells[1] = int(init[1])
        inst += 1
    elif x == 0 or x == 1:
        print(cells[x], end=" ")
        inst += 1
    else:
        cells[x % 2] += int(x / abs(x))
        if cells[x % 2] == -1:
            inst += 1
        else:
            inst = abs(x) // 2
while inst < len(prgm):
    ichi(prgm[inst])