Add rainbow test script

Rainbow/rainbow.js

@@ -0,0 +1,37 @@
+// Approximate racket functions
+function circle(color) {
+    print(`${color} circle`)
+}
+function square(color) {
+    print(`${color} square`)
+}
+function print(shape) {
+    console.log(shape)
+}
+// Cuz javascript doesn't have functional primitives
+function first(list) {
+    return list[0]
+}
+function rest(list) {
+    return list.slice(1)
+}
+
+// Helper to cycle through the functions
+function cycle(list) {
+    return rest(list).concat(first(list))
+}
+
+// The actual function
+function rainbow(...functions) {
+    let colors = ['red', 'orange', 'yellow', 'green', 'blue', 'indigo', 'violet']
+    function rainbowRecursive(functions, colors) {
+        if (colors.length === 0) {
+            return
+        }
+        first(functions)(first(colors))
+        rainbowRecursive(cycle(functions), rest(colors))
+    }
+    rainbowRecursive(functions, colors)
+}
+
+rainbow(circle, square)

Rainbow/rainbow.rkt

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+#lang racket
+(require pict)
+(require pict/color)
+; The actual function
+(define (rainbow . shapes)
+  (define colors (list red orange yellow green blue purple))
+  (define (cycle lst) (append (rest lst) (list (first lst))))
+  (define (rainbow-recursive shapes colors)
+    (cond
+      [(empty? colors) (void)]
+      [(print((first colors) (first shapes)))
+       (rainbow-recursive (cycle shapes) (rest colors))]
+      )
+    )
+  (rainbow-recursive shapes colors))
+; Example usage
+(rainbow (filled-rectangle 25 25) (filled-ellipse 25 25))