1. PLT Final Project---COLOGO Lixing Dong, Zhou Ma, Chao Song, Siyuan Lu, Dongyang Jiang

2. Overview of COLOGO Columbia LOGO Motivation: For educational use 1. an effective programming language for drawing 2D graphics 2. designed in spirit of low threshold, easily implemented.

3. Function Feature Euclidean Pictures Creating Functions Recursive Iridescent Simple Data Structure such as Array. Support direct HTML and Javascript Output

4. COLOGO VS. LOGO Colorful Compile together No list

5. Language Tutorial

6. Some examples of our program Fibonacci Recursive

7. Some examples of our program Olympic Rings (faked)

8. Rainbow Some examples of our program

9. Language Tutorial Variable Declaration Int a,b; Bool c; foo d; (:foo is a object:) Int e[10]; (:array:)

10. Language Tutorial Expression Assignment: a = 1; c = True; Arithmetic Expression: a = b + a; Comparison Expression: c = a < b; Logical Expression: c = (a == b); Not c; Function call: a = testfunc(b); Comment: (:This is a comment:)

11. Language Tutorial Loop Loop(10) { a = a + 1; } Loop(10) { a = a + 1; Break; } Loop(10) { a = a + 1; Goon;}

12. Language Tutorial Condition If (c) { a = b; } End If (c) { a = b; } Else { b = a; } End

13. Language Tutorial Jump If (c) { a = b; } End If (c) { a = b; } Else { b = a; } End

14. Language Tutorial Draw Move Forward: FD 10; Move Backward: BK 10; Turn Left: LF 90; Turn Right: RT 90;

15. Language Tutorial Draw Reset position: RESET; Clear Screen: CLS; Pen Operation: PU; PD; PF; Line Width: WD 10; Set Line Color: RGB 255, a, e[2]

16. Language Tutorial Function Declaration: Func testfunc(int n) : int { Return n;} Call: a = testfunc(b);

17. Language Tutorial Object Definition: Obj foo { int bar; int baz;} Declaration: foo d; Reference: dot operator d.bar = a; b = d.baz;

18. Implementation

19. Layout

20. Flow Ast: Abstract Syntax Tree Types Definition One Rule -> One Type Constructor

21. Flow Scanner: Generate Tokens Parser: Generate AST Use Type Constructor Defined in AST

22. Flow Scanner: Generate Tokens Parser: Generate AST Use Type Constructor Defined in AST Basic Error Recovery

23. Flow Semantic: Traversal of AST, Checking Variables, Function Definitions, Type Matching, etc. Generator: Traversal of AST, Generate JS code in HTML file Printer: Traverse and print the AST

24. Flow Semantic: Traversal of AST, Checking Variables, Redefinition Type Matching: Array Object Function Matching Parameter Count, Argument Type Return Type Definition Scope Stack faked by List Small Features: infinite loop

25. Flow Generator: Traversal of AST Generate JS Code in HTML5 file Draw Statement Array in Obj

26. Flow

27. SUMMARY Further to develop Lessons learned