# ｛｝

{} is a family of esolangs by User:PythonshellDebugwindow.

## Level 1

{} Level 1 was the first attempt at an esolang in the {} family, although it was horribly ambiguous, too much so to parse (for human and machine alike). It uses an unbounded signed integer accumulator called acc.

### Commands

Command Meaning
`{}` 0
`{{x}}` While acc > 0 do x (x can be any number of commands > 0)
`{x}` Set acc to x
`{x{y}` x + y
`{{}}` acc

A `{}` as x inside a `{x}` is indistinguishable from a `{{}}`.

### Computational class

Due to its ambiguity, Level 1 is uncomputable.

## Level 2

{} Level 2 was the second attempt at an esolang in the {} family. Like Level 1, it was too ambiguous to program in, and it uses an unbounded signed integer accumulator called acc.

### Commands

Command Meaning
`{}` 0
`{x}` acc = x (also evaluate to x)
`{xy}` If x then do y (y can be any number of commands > 0)
`{{xy}}` While x ≠ 0 do y (y can be any number of commands > 0)
`{{}}` acc
`{{x}}` acc + x + 1

### Computational class

Like Level 1, Level 2 is uncomputable due to its excessive ambiguity.

## Level 3

{} Level 3 was the third attempt at an esolang in the {} family, and the first successful (i.e. non-ambiguous) one. It uses an unbounded signed integer accumulator called acc.

### Commands

Command Meaning
`{}` 0
`{{}}` ++acc
`{{x}}` acc = x
`{xy}` While acc ≠ x do y (y can be any number of commands > 0)

### Computational class

Level 3 might be a push-down automaton, as its single accumulator can be incremented and reset (but not much else).

## Level 4

{} Level 4 was the fourth attempt at an esolang in the {} family, and the second successful one. It uses an unbounded signed integer accumulator called acc.

### Commands

Command Meaning
`{}` -1
`{{}}` acc
`{{x}}` acc = x
`{{xy}}` x - y
`{xy}` While acc ≠ x do y (y can be any number of commands > 0)

### Computational class

{} Level 4 is a push-down automata, as it has only one accumulator and no instructions to multiply/divide by a constant. (I could be wrong...)

## Level 5

{} Level 5 was the fifth attempt at an esolang in the {} family, and the third successful one. It uses an array of unbounded signed integer registers called accs (the array is called accs). The array also has negative indices.

### Commands

Command Meaning
`{}` -1
`{{xy}}` x - y
`{{{xy}}}` accs[x] = y
`{{{x}}}` accs[x]
`{{xyz}}` While accs[x] != y do z (z can be any number of commands > 0)

### Computational class

{} Level 5 is Turing complete. See the talk page for proof.

## Level 6

{} Level 6 is the sixth esolang in the {} family, and the fourth successful one. It uses a bit called N and an array of integers called accs.

### Commands

Command Meaning
`{}` -1
`{{}}` Nop
`{{{x}}}` accs[N] += x
`{{xy}}` x - y
`{xy}` While accs[N] ≠ x do y (y can be any number of commands > 0)

After each command, N is swapped between 0 and 1.

### Computational class

Level 6 has an unknown computational class, although by padding with nops, it could possibly be used to write programs.

## Level 7

{} Level 7 is the seventh esolang in the {} family, and the fifth successful one. It uses a bit called N initialized to 0 and an array of two unbounded signed integers (the array is called accs) each initialized to 0.

### Commands

Command Meaning
`{}` -1
`{{}}` accs[N]
`{{x}}` While accs[N] ≠ 0 do x (x can be any number of commands > 0 and ≠ 2)
`{{xy}}` x - y
`{xy}` x + y

After each command, N is swapped between 0 and 1.

### Computational class

Level 7 is Turing-complete, as it could simulate a two-register Minsky machine. (You can use `{}` on its own as a nop.)

## Level 8

{} Level 8 is a brainfuck equivalent, making it the first esolang in the {} family known to be Turing-complete.

### Commands

Level 8 Brainfuck
`{}` `+`
`{{}}` `-`
`{{}{}}` `>`
`{{}{}{}}` `<`
`{{}{}{}{}}` `,`
`{{}{}{}{}{}}` `.`
`{{p}}` `[p]`

Note that for the instruction `{{p}}` (`[p]`), p cannot be empty; if it is, the instruction will be treated as `{{}}` (`-`).

### Computational class

Since Level 8 is a brainfuck equivalent, it is Turing-complete.