Added Typed Racket.

WTF this language actually sucks.

04-typed-racket/main.rkt

@@ -0,0 +1,44 @@
+#lang pl
+
+; I'm keeping my own type declarations bc the racket ones are literally unreadable.
+; gcd2: a: Int, b: Int → Int
+(: gcd2 : (Integer Integer -> Integer))
+; Given two non-negative integers, determine their greatest common divisor.
+(define (gcd2 a b)
+  (cond
+    [(or (negative? a) (negative? b)) (error 'neg "Given negative number.")]
+    [(= a 0) b]
+    [(= b 0) a]
+    [(and (even? a) (even? b)) (* 2 (gcd2 (floor (/ a 2)) (floor (/ b 2))))]
+    [(even? b) (gcd2 a (floor (/ b 2)))]
+    [(even? a) (gcd2 (floor (/ a 2)) b)]
+    [else
+     (if (<= a b)
+         (gcd2 a (- b a))
+         (gcd2 b (- a b)))]))
+
+(test (gcd2 0 0) => 0)
+(test (gcd2 288 64) => 32)
+; What's the point of the symbol in the error definition if it isn't used to check errors?
+(test (gcd2 2 -1) =error> "Given negative number.")
+
+; out-of-bounds?: start: Number,
+;                 lower: Number,
+;                 upper: Number, 
+;                 l: [Number] → Bool
+(: out-of-bounds? : (Number Number Number (Listof Number) -> Boolean))
+; Determines if an object that begins at the starting location and then moves delta by delta ever ever steps outside of the bounds (inclusive).
+(define (out-of-bounds? start lower upper l)
+  (if (or (< start lower) (> start upper))
+      #t
+      (match l
+        ['() #f]
+        [(cons frst rst) (out-of-bounds? frst lower upper rst)])))
+
+(test (out-of-bounds? 0 -1 2 '(0 -2 3 -4 6)) => #t)
+(test (out-of-bounds? 0 -1 1 '(1)) => #f)
+(test (out-of-bounds? 0 -1 1 '()) => #f)
+(test (out-of-bounds? 0 1 2 '()) => #t)
+(test (out-of-bounds? 0 0 0 '()) => #f)
+
+