Karel for ruby

This is a minimalist implementation of a karel-the-robot system in ruby.

Usage

require_relative "./karel"

Karel.run("world1") do
  move
  move
  turn_left
  move
  move
  if next_to_a_beeper?
    pickup_beeper
  end
end

Programming Karel

Commands / Procedures

A command tells karel to take an action that affects his world:

• move Moves karel one space in the direction he is facing. If the space is blocked, will cause karel to crash.
• turn_left
• pickup_beeper Moves a beeper from karel's current space to his beeper bag. If there are no beepers present, will cause karel to crash.
• put_beeper Moves a beeper from karel's beeper bag to his current space. If there are no beepers in his bag, will cause karel to crash.

Queries / Predicates / Functions

A query allows us to ask questions about karel's world:

• front_clear?
• front_blocked?
• left_clear?
• left_blocked?
• right_clear?
• right_blocked?
• back_clear?
• back_blocked?
• next_to_a_beeper?
• not_next_to_a_beeper?
• any_beepers_in_beeper_bag?
• no_beepers_in_beeper_bag?
• facing_north?
• facing_south?
• facing_east?
• facing_west?
• not_facing_north?
• not_facing_south?
• not_facing_east?
• not_facing_west?

Loops

while <predicate>
end

Move until we're about to hit a wall:

while front_clear?
  move
end

Turn until we can move:

while front_blocked?
  turn_left
end

Pick up all the beepers on the current space:

while next_to_a_beeper?
  pickup_beeper
end

Defining methods

We can build our own version of the built-in methods using def. Place these before the call to Karel.run.

def about_face
  turn_left
  turn_left
end

Karel.run("world1") do
  about_face
end