LOGO
"Turtle Graphics“ for kids.
History
Logo: from Greek logos for “word”
Developed by a team at MIT in 1960s
Notable: Seymour Papert
Mathematician from Geneva
Worked with Piaget who influenced him
Designed as a dialect of LISP
Why the Turtle?
Originally a robotic creature sat on floor
Domed shape with shell-like electronics casing
Slow movement of device
Directed to move around and draw by typing
commands at computer
Designed to be programmed by children
Less expensive version created on computer
Evolution
130 existing implementations
1977 1985 1993
1967 2003
TILOGO
Apple LOGO
Atari Logo
IBM Logo
Logo Learner LOGO PC WIN Comenius Logo
MacLogo LOGO LOGO Logo Grafico
Writer
Object Logo
LEGO
MicroWorlds Mach Turtles Logo
LOGO LOGO UCB Logo
MSWLogo
Driven by commercial and regional factors
Language Concepts
Basic commands
Control Structures
while condition [instruction list]
until condition [instruction list ]
repeat number [instruction list]
Recursion (preferred paradigm)
Scoping
Global variables: if not declared before use
Local variables:
may be declared
Input variables for functions are local
Basic commands
Forward 100 (FD 100) - moves the turtle
forward 100 units
Back 50 (BK 50) - moves the turtle back 50
units
Right 45 (RT 45) - turns the turtle 45 degrees
to the right
Left 90 (LT 90) - turns the turtle 90 degrees to
the left
Home - Returns the turtle to its origin
ClearSceen (CS) - Erases the screen
Features
Graphics / Music
Extensibles: basic operations “primitives.”
Working Definitions: allows for user-
defined new definitions
Modularity
Interactivity
Flexibility
Recursion
to spiral :size
if :size > 30 [stop] ; a condition stop
fd :size rt 15 ; many lines of action
spiral :size *1.02 ; the tailend recursive call
end
MSW LOGO Implemenation
Source: http://www.softronix.com
Example: Square
Turtle Moves forward
and turns 90º 4 times
REPEAT 4 [FD 100 RT 90]
Source: http://mckoss.com/logo/
Examples
Source: http://www.yukoncollege.yk.ca/
Future of Logo
New Releases of LOGO:
NetLogo
Parallel modeling and simulation
Northwestern University
StarLogo
MIT