;; The first three lines of this file were inserted by DrRacket. They record metadata
;; about the language level of this file in a form that our tools can easily process.
#reader(lib "htdp-intermediate-lambda-reader.ss" "lang")((modname week6_m_full) (read-case-sensitive #t) (teachpacks ((lib "image.ss" "teachpack" "2htdp"))) (htdp-settings #(#t constructor repeating-decimal #f #t none #f ((lib "image.ss" "teachpack" "2htdp")))))
; write the function addntoall, which adds n to every
; number in a given list

; addntoall : number list-of-numbers -> list-of-numbers
; adds given number to each element of list
(define (addntoall n lon)
  (map (lambda (x) (+ n x)) lon)
  )

(check-expect (addntoall 5 (list 1 2 3)) (list 6 7 8))
(check-expect (addntoall 0 empty) empty)

; foldr : (X Y -> Y) Y list-of-X -> Y

; (foldr + 0 (list 1 2 3)) ---> 6
; (foldr * 1 (list 2 3 4)) ---> 24
; (number number -> number) number list-of-numbers -> number

; (foldr first-doll-or-else false (list 'cheese 'doll 'car))
; (symbol boolean -> boolean) boolean list-of-symbols -> boolean

; signature of foldr?

(define (drop p? l)
  (filter (negate p?) l))

(define (negate p)
  (local [(define (negated-predicate x)
            (not (p x)))]
    negated-predicate))


(define mycons2 (cons 'banana (cons 'apple empty)))

(define (f x) (* x 3))
; is equivalent to:
;(define f (lambda (x) (* x 3)))

(f 4)

(define adder
  (lambda (x) (lambda (y) (+ x y))))

; signature?
; adder : number -> (number -> number)

(define xx (adder 3))

( 5)