1 files changed, 10 insertions, 1 deletions
diff --git a/src/util.js b/src/util.js
index 74233f4..ecae45e 100644
--- a/src/util.js
+++ b/src/util.js
@@ -10,7 +10,7 @@ export function create(obj, proto=Object.prototype) {
 };
 
 
-export function random_choice(collection, r) {
+export function random_choice(collection, r=Math.random()) {
   const idx = Math.floor(collection.length * r);
   return collection[idx];
 }
@@ -41,3 +41,12 @@ export function deepEqual(a, b, debug=false) {
     return a === b;
   }
 }
+
+
+export function apply(f, n, x0) {
+  if (n == 0) {
+    return x0;
+  } else {
+    return f(apply(f, n-1, x0));
+  }
+}