adds first and rest

desktop/sources/scripts/library.js

@@ -28,10 +28,19 @@ function Library (ronin) {
     console.log(...args)
   }
 
+  // Arrays
   this.map = (fn, arr) => {
     return arr.map(fn)
   }
 
+  this.first = (arr) => {
+    return arr[0]
+  }
+
+  this.rest = ([_, ...arr]) => {
+    return arr
+  }
+
   // Rects
 
   this.pos = (x, y, t = 'pos') => {