Tur - Turing Machine Language

Tur is a language for defining and executing Turing machines, complete with parser, interpreter, and multi-platform visualization tools. It supports both single-tape and multi-tape configurations.

Web	TUI

Language Overview

Tur (.tur files) provides a clean, readable syntax for defining both single-tape and multi-tape Turing machines. The language includes:

• Declarative syntax for states, transitions, and tape configurations
• Multi-tape support with synchronized head movements
• Built-in validation and static analysis
• Cross-platform execution via CLI, TUI, and web interfaces

Syntax Examples

Single-Tape Turing Machine

name: Binary Counter
tape: 1, 0, 1, 1
rules:
start:
0 -> 0, R, start
1 -> 1, R, start
_ -> _, L, inc # Reached end, go back to start incrementing
inc:
0 -> 1, S, done # 0 becomes 1, no carry needed
1 -> 0, L, inc # 1 becomes 0, carry to next position
_ -> 1, S, done # Reached beginning with carry, add new 1
done:

Multi-Tape Turing Machine

name: Copy Tape
tapes:
[a, b, c]
[_, _, _]
rules:
copy:
[a, _] -> [a, a], [R, R], copy
[b, _] -> [b, b], [R, R], copy
[c, _] -> [c, c], [R, R], copy
[_, _] -> [_, _], [S, S], done
done:

Language Specification

Program Structure

Every .tur program consists of:

name: Program Name
# Single-tape configuration
tape: symbol1, symbol2, symbol3
head: 0 # optional, defaults to 0
# OR multi-tape configuration
tapes:
[tape1_symbol1, tape1_symbol2]
[tape2_symbol1, tape2_symbol2]
heads: [0, 0] # optional, defaults to [0, 0, ...]
# Optional blank symbol (defaults to ' ')
blank: ' '
# Transition rules
rules:
state_a:
input -> output, direction, next_state
# ... more transitions
state_b:
# ... transitions

Note

The first state defined in the rules: section is automatically considered the start state. In the examples above, state_a is the initial state because it appears first.

Transition Rules

Single-tape format:

current_symbol -> write_symbol, direction, next_state

Multi-tape format:

[sym1, sym2, sym3] -> [write1, write2, write3], [dir1, dir2, dir3], next_state

Directions

• L or < - Move left
• R or > - Move right
• S or - - Stay (no movement)

Comments

# This is a comment
state:
a -> b, R, next # Inline comment

Special Symbols

• The underscore (_) is a special symbol used to represent a blank character in program definitions.
• Any other character or unicode string can be used as tape symbols.
• The blank symbol can be customized using the blank: directive in the program.

Platforms

Command Line Interface (CLI)

# Run a program
cargo run -p tur-cli -- examples/binary-addition.tur
# Pipe input to a programecho'$011'| cargo run -p tur-cli -- examples/binary-addition.tur
# Chaining programs with pipesecho'$011'| cargo run -p tur-cli -- examples/binary-addition.tur | cargo run -p tur-cli -- examples/binary-addition.tur

Terminal User Interface (TUI)

# Interactive TUI with program selection
cargo run --package tur-tui

Documentation

• API Documentation: docs.rs/tur
• Repository: github.com/rezigned/tur
• Examples: See the examples/ directory for sample .tur programs

License

• MIT License (LICENSE)