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; rough exam format:
; - 40% multiple choice
; - 40% short answer
; - 1-2 "write a program" questions

; things to know:

; 1) evalute stuff

; example: what does the following evaluate to:
(+ 5 (- 4 3))
; => (+ 5 1) => 6
; Answer: 6

; know, for example, cond and if evaluation rules

(define (f x) 
  (cond [(= x 0) 1]
        [else (f (- x 1))]))

; exceptions to general eval rule: cond, if, define, define-struct ...

; 2) define/execute a function

; what does the following do?

(define (f x) (+ x 1))
(f 5)
; (f 5) => (+ 5 1) => 6

; 3) Design recipe

; what are the steps of the design recipe?

; data
; signature, purpose, header
; examples
; template
; body
; tests

; 4) Data definitions

; compound:
; an invention-event is a:
; - symbol inventor
; - symbol item 
; - number year
(define-struct invention-event (inventor item year))

; functions we get:
; (make-invention-event ...), (invention-event? ...)
; selectors: (invention-event-inventor ...), etc.

; conditional:
; a list-of-numbers is either:
; - empty, or
; - (cons number list-of-numbers)


; 5) Templates
; Know how to generate templates for conditional and compound data.
; compound:
;(define (fun-for-ie ie)
;  ( ... (invention-event-inventor ie) ...
;    ... (invention-event-item ie) ...
;    ... (invention-event-year ie) ...)

; conditional:
; (define (fun-for-lon lon)
;   (cond [(empty? lon) ...]
;         [(cons? lon) 
;           (...(first lon)...(fun-for-lon (rest lon))...)] 
;    ))

; 6) Recursion
; structural (as in fun-for-lon above)
;     know:
;      lists
;      trees

; generative
;     know about:
;       base cases
;       infinite recursion

; 7) Binary search trees
; example question: given 5 nodes, draw the corresponding BST.
; know how to find nodes within a BST

; 8) Local
; Know what it means
; example question, what does the following evaluate to?
(define (g x) (local [(define (g y) (+ x 4))] (g 3)))
(g 5)

; 9) lambda
; know how to define functions with lambda and pass as args, return from functions

; example: write a function "fun-to-add-x" that returns a function
; that will add a passed-in value x to a number input

; fun-to-add-x : number -> (number -> number)
(define (fun-to-add-x x)
  (lambda (y) (+ y x)))

; 10) map/filter

; example: write an expression that negates all numbers in a list of numbers lon1
(map (lambda (x) (- x)) lon1)
;or
(map - lon1)

; 11) Signatures:
; what's the signature for map?
; map: (X -> Y) list-of-X -> list-of-Y

; know how to write signatures with variables and functions as arguments