wheatwizard / pebbles

Pebbles

Pebbles is a language with 4 pebbles and an infinite beach.

Interpretation

Pebble is read left to right with certain characters performing certain actions.

Memory

Pebble's memory is an infinte tape of ones and zeros extending in both directions.

Exactly 4 cells on the tape will be on at any point, never more, never less.

There is a read head that is always positioned between two adjacent cells

Commands

• ] Move the read head right

• [ Move the read head left

• > Add the bit to the right to the output

• < Add the bit to the left to the output

• ~ Switch the bit to the left with the bit to the right

• _( Begin loop, _ represents a predicate

• ) End loop

Loops

A loop will be entered if the two bit adjacent to the read head fails to meet a predicate. A loop will be run repeatedly until the predicate is failed on a ).

Predicates

• & performs logical and on the two bits

• | performs logical or on the two bits

• ^ performs logical xor on the two bits

• !_ negates the next predicate

Running Pebbles

Currently Pebbles can be called in interactive mode using:

$ ghci Pebbles.hs

To run a program call the function pebble with the source as an argument. Example:

Prelude> pebble "[[<>"