Hasking

      __ __         __    _          
     / // /__  ___ / /__ (_)__  ___ _
    / _  / _ `(_-</  '_// / _ \/ _ `/
   /_//_/\_,_/___/_/\_\/_/_//_/\_, / 
                              /___/  

A very very simple Turing Machine simulator and interpreter written in Haskell.

Compile and run

You will need Stack to compile this project, and then you can just do the following

git clone http://github.com/micheleberetta98/hasking
cd hasking
stack setup
stack build

Use stack run -- [options] to run the project.

There are some tests that you can execute with stack test (currently borked).

Command line options

The options are as follow

hasking ((-v | --version) | COMMAND (--stdin | INPUT))

• -v/--version prints the version
• -h/--help shows the help page
• INPUT is the name of a Hasking file (use --stdin to read from standard input)
• COMMAND is one between
  • run to execute a Hasking file
  • sim that runs a simulation of a machine (-m/--machine) on a tape (-t/--tape)

Simulation

When you are in the simulation mode, you have to specify both what machine in the file to simulate and what tape to use (or just leave it empty).

The language

In any single file, you can define both machines and simulations: machines have a name and some more properties, while simulations specify a machine and a tape that is feed into it.

The general form is:

; Comments are what follows a ;

(machine <name>
  initial <initial state>
  finals (<list of final states>)
  rules (<list of rules>))

(simulation <machine name> (<tape symbols>))

Symbols are any single char, excluding one of ; .[](), and . is the special blank symbol. State names are just like variables in other languages: alphanumeric strings that start with a letter.

You can see some examples in examples.

Rules

State transitions are in the form of

(<state> <symbol> <state> <symbol> <direction>)

Where direction is one of L (go left), R (go right) or S (stay.)

For example, (s 1 q 0 R) means

• If the machine is in the state s and is reading 1 off the tape
• Go to state q, write 0 onto the tape and then move Right