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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?.
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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
Object Logo MacLogo Logo Learner IBM Logo Comenius Logo WIN LOGO PC LOGO LEGO LOGO LEGO LOGO Evolution • 130 existing implementations • Driven by commercial and regional factors 1977 1985 1993 1967 2003 TILOGO Apple LOGO Atari Logo LOGO Writer Logo Grafico MicroWorlds LOGO Mach Turtles Logo UCB Logo MSWLogo
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 actionspiral :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