sexp-on-the-beach.scm

#lang racket

(require compatibility/defmacro)

'(monkey . peanuts)

'(eenie . (meenie . (meiney . (moe . ()))))

'(eenie meenie meiney moe)

"I like peanut butter"

(string->list "I like peanut butter")

(map char->integer (string->list "I like peanut butter"))

'((monkey . animal)
  (peanut . vegetable)
  (africa . continent)
  (sambal . condiment))

'(VP
  (NP I)
  (VP (VP like)
      (NP (NP peanut)
          (NP butter))))

(λ (x) x)

((λ (x) x) 42)

(define do-nothing (λ (x) x))

(do-nothing 42)

(* 2 5)

(define double (λ (x) ( * x 2)))

(double 5)

(let ((x 3)
      (y 5))
  (if (> (* x y) 20)
      "x * y is greater than 20"
      "x * y is not greater than 20"))

(define >20
  (λ (x)
     (> x 20)))

(let ((x 100)
      (y 3))
  (>20 (/ x y)))

(define >checker
  (λ (compare-to)
     (λ (x)
        (> x compare-to))))

(define >50
  (>checker 50))

(let ((x 100)
      (y 3))
  (>50 (/ x y)))

(defmacro unless (condition body)
  (if (not condition)
      body
      ''()))

(unless #f
        "Didn't happen")

(defmacro repeat (times body)
  (letrec ((rep (λ (times body)
                  (if (> times 0) 
                      (cons body (rep (- times 1) body))
                      '()))))
    (rep times body)))

(repeat 3
        (display "Hello\n"))