Robot Language

What is Robot Laguage

• The language for drawing recursive curves
  
• Turtle Graphics based
  
• Very simple programming language
  
• Robot has an ACC for holding an iteration count
  
• The original Robot specification and implimentation:
  Litchen Wang,
  An Interactive programming Language for control of robots, DDJ, Vol.2, Issue 10, pp.60-63 (1977).
  

Syntax

<Expression> ::= <Term><Funcion> | <Term>(<Expression>) | <Expression><Expression>

Robot executes an <Expression>.
<Term> specifies an iteration count of following one.

<Term> ::= a | <Number> | nothing

nothing means 1.
"a" means a content of Acc.

<Number> ::= 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | <Number><Number>

0 means 2^31.

<Function> ::= <BuiltinFunction> | <UserFunction>

<BuiltinFunction> , <UserFunction> as follows.

Builtin Functions

+

Increment Acc

-

Decrement Acc

h

Move to the center of the display. (Home)

n

set direction up. (North)

c

clear display

r

rotate right 45 degree

f

forward 1 step with drawing a line.

j

forward 1 step without drawing a line. (Jump)

t(<NonZeroExpression>)(<ZeroExpression>)

if Acc!=0 then execute <NonZeroExperssion>
if Acc==0 then execute <ZeroExperssion>

dF(<DefunExpression>)

define <UserFunction> F as <DefunExpression>.
The character F is a name of <UserFunction>.

Reserved Words

a

Acc placed as term, means a value of ACC.
Robot has an ACC.
(ACC holds a value , 0-2^31)

:

indicates commnad, preceeding an command.
Commnad is a special feature of KRobot.
There is no command in original Robot specification.

UserFunction

Commands

:d

display all <UserFunction>.

:n

clear all <UserFunction>. (New)

:<Trem>s

set dots of a step as <Trem>.

Buttons

Clear

Clear display

Getd

Get and display the Definitions of <UserFunction> .
This button has no effect to the stack of KRobot

CI

Clear the Input line

?

display help

DoIt

exectute the input line

Cont

resume stopped execution

Stop

Stop the execution

Startup execution

Execution Example

Dragon curve dx(t(-x6rk+)(f)) dk(t(-x2rk+)(f)) chna-10+x
Hilbert curve du(t(-vfxuyfufxv+)(x)) dv(t(-uyfvfxvyfu+)(y)) dx(6r) dy(2r) chna-5+2ru
Sierpinsky curve dx(t(-xfxufuxfx+)(v)) du(5r) dv(2r) dy(6r3r4(fx)) chna-2+y