CSE 111, Fall 04, KAREL PROGRAMMING SUMMARY

CSE 111, Fall 2004

KAREL PROGRAMMING SUMMARY

The following summary of Karel the Robot's programming language is adapted from:

Pattis, Richard E.; Roberts, Jim; & Stehlik, Mark (1995), Karel the Robot: A Gentle Introduction to the Art of Programming, Second Edition (New York: John Wiley & Sons).

1. PRIMITIVE (OR: "BASIC") INSTRUCTIONS

SYNTAX (what the instruction looks like in Karel's lang	SEMANTICS (what the instruction means (i.e., what Karel does)
1. `move`	IF Karel sees no walls, THEN Karel moves forward 1 block in direction he's facing ELSE IF Karel sees a wall, THEN "error shutoff"
2. `turnleft`	Karel pivots 90° left
3. `pickbeeper`	IF there is at least one beeper on Karel's corner, THEN Karel picks up one beeper & puts it in his bag ELSE error shutoff
4. `putbeeper`	IF there is at least one beeper in Karel's bag, THEN Karel puts it on his corner ELSE error shutoff
5. `turnoff`	Karel turns himself off

2. BLOCK-STRUCTURING (OR "SEQUENCING")

6.    begin
         <instruction>
               .
               .
               .
         <instruction>
      end

3. CONDITIONAL (OR "CHOICE", OR "SELECTION")
INSTRUCTIONS

7. if <test>
then <instruction>

8.    if <test>
          then <instruction>
          else <instruction>

4. REPETITION (OR "LOOPING") INSTRUCTIONS

9. iterate <positive-number> times
<instruction>

10. while <test> do
<instruction>

5. MECHANISM FOR DEFINING (OR "NAMING")
NEW INSTRUCTIONS

define-new-instruction <new-name> as
<instruction>

6. SPECIFYING A COMPLETE PROGRAM

beginning-of-program
   define-new-instruction <new-name> as
        <instruction>;
            .
            .
            .
   define-new-instruction <new-name> as
        <instruction>;
    beginning-of-execution
        <instruction>;
            .
            .
            .
        <instruction>
end-of-execution
end-of-program

7. ANGLE-BRACKETED WORDS

<instruction>	Any of Karel's instructions 1 - 10
<new-name>	Any new non-reserved word, using lower-case letters, numbers, &/or "-")
<positive-number>	Any positive number
<test>	Any of the following: `front-is-clear, front-is-blocked` `left-is-clear, left-is-blocked` `right-is-clear, right-is-blocked` `next-to-a-beeper, not-next-to-a-beeper` `facing-north, not-facing-north` `facing-south, not-facing-south` `facing-east, not-facing-east` `facing-west, not-facing-west` `any-beepers-in-beeper-bag, no-beepers-in-beeper-bag`

file: 111F04/karel-prog-sum-2004-09-26.html