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The TeachScheme! Project

The TeachScheme! Project. Adelphi University Brown University Northeastern University University of Chicago University of Utah Worcester Polytechnic Institute. The Revolution. Two principles:. Shift away from machine details.

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The TeachScheme! Project

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  1. The TeachScheme! Project Adelphi University Brown University Northeastern University University of Chicago University of Utah Worcester Polytechnic Institute

  2. The Revolution Two principles: Shift away from machine details Emphasis on correctness over efficiency (ie, focus on program design)

  3. What’s Wrong withMachine-Oriented Languages? • Make students waste time on unimportant and uninteresting details • Force students to confront issues they are not prepared for • and ... machine arithmetic, pointers and memory addresses, even i/o

  4. What Computer Scienceis Not About The computer! Just as biology isn’t “microscope science” and writing isn’t “pen science” ...

  5. What’s This AboutProgram Design?

  6. Why Am I Here? • The TeachScheme! Project: Outreach program hosted by six universities • Specially designed for high schools • Provides all material -- books, software, etc -- free of charge

  7. What Teachers Experience

  8. Scheme 90% Problem-solving vs 10% Syntax K.I.S.S.Keep It Simple Syntactically C++/Pascal 10% Problem-solving vs 90% Syntax

  9. The Golden Rule ofScheme Syntax ( ) Operation List-of-Arguments or ( Operation Arg1 )

  10. The Golden Rule ofScheme Syntax ( ) Operation List-of-Arguments or ( Operation Arg1 Arg2)

  11. The Golden Rule ofScheme Syntax ( ) Operation List-of-Arguments or ( Operation Arg1 Arg2 . . . Argn )

  12. An Example From Arithmetic 4 + 5 ( Operation Arg1 Arg2 )

  13. Example #1 (cont’d) 4 + 5 ( Operation Arg1 Arg2 ) ( )

  14. Example #1 (cont’d) 4 + 5 ( Operation Arg1 Arg2 ) ( + )

  15. Example #1 (cont’d) 4 + 5 ( Operation Arg1 Arg2 ) ( + 4 )

  16. Example #1 (cont’d) 4 + 5 ( Operation Arg1 Arg2 ) ( + 4 5 )

  17. Example #1 (cont’d) 4 + 5 ( + 4 5 )

  18. Another Arithmetic Example ( 4 + 5 ) · 6

  19. Example #2 (cont’d) ( 4 + 5 ) · 6 ( )

  20. Example #2 (cont’d) ( 4 + 5 ) · 6 ( * )

  21. Example #2 (cont’d) ( 4 + 5 ) · 6 ( * ( + 4 5 ) )

  22. Example #2 (cont’d) ( 4 + 5 ) · 6 ( * ( + 4 5 ) 6 )

  23. Example #2 (cont’d) ( 4 + 5 ) · 6 ( * ( + 4 5 ) 6 )

  24. An Example From Algebra 4 + 5 f( x ) = x + 5

  25. Example #3 (cont’d) f( x ) = x + 5 ( Operation Arg1 Arg2 )

  26. Example #3 (cont’d) f( x ) = x + 5 ( Operation Arg1 Arg2 ) ( )

  27. Example #3 (cont’d) f( x ) = x + 5 ( Operation Arg1 Arg2 ) ( define )

  28. Example #3 (cont’d) f( x ) = x + 5 ( Operation Arg1 Arg2 ) ( function-name input-name ) ( f x )

  29. Example #3 (cont’d) f( x ) = x + 5 ( Operation Arg1 Arg2 ) ( define ( f x ) )

  30. Example #3 (cont’d) f( x ) = x + 5 ( Operation Arg1 Arg2 ) ( output-rule ) ( + x 5 )

  31. Example #3 (cont’d) f( x ) = x + 5 ( Operation Arg1 Arg2 ) ( define ( f x ) ( + x 5 ) )

  32. Example #3 (cont’d) f( x ) = x + 5 ( define ( f x ) ( + x 5 ) )

  33. Algebra Pascal Programf(Input, Output) ; Var x : Integer ; Begin Readln(x); Writeln (x + 5) End . f (x) = x + 5 Scheme ( define( f x ) (+ x 5 ) ) Algebra vs Scheme vs Pascal

  34. Design

  35. D3: Data Drive Design(A Non-Numeric Example) Consider program guest, which determines whether a friend’s name is in a party’s invitation list.

  36. Mathilde . . . John . . . Is Mathilde In The List? No Yes Look in the Rest of the List

  37. Mathilde Sherry . . . . . . Is Mathilde InThe Rest of the List? No Yes Look in the Rest of the List

  38. Pattern To Algebra

  39. Algebra guest ( name, list ) =

  40. Algebra guest ( name, list ) =

  41. Algebra guest ( name, list ) = if list is empty

  42. Algebra guest ( name, list ) = no if list is empty

  43. Algebra guest ( name, list ) = no if list is empty if name = first ( list )

  44. Algebra guest ( name, list ) = no if list is empty yes if name = first ( list )

  45. Algebra guest ( name, list ) = no if list is empty yes if name = first ( list ) otherwise

  46. Algebra guest ( name, list ) = no if list is empty yes if name = first ( list ) guest ( name, rest ( list )) otherwise

  47. Algebra guest ( name, list ) = Scheme ( define ( guest name list ) )

  48. Algebra guest ( name, list ) = Scheme ( define ( guest name list ) )

  49. Scheme ( define ( guest name list ) ( cond )) Algebra guest ( name, list ) =

  50. Algebra guest ( name, list ) = if list is empty if name = first ( list ) otherwise Scheme ( define ( guest name list ) ( cond ))

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