orbis-higherorderFunction

Exercises/1-callback.js

@@ -1,5 +1,11 @@
 'use strict';
 
-const iterate = (obj, callback) => null;
+const iterate = (obj, callback) => {
+  const keys = Object.keys(obj);
+  for (const key of keys) {
+    const value = obj[key];
+    callback(key, value, obj);
+  }
+};
 
 module.exports = { iterate };

Exercises/2-closure.js

@@ -1,5 +1,5 @@
 'use strict';
 
-const store = x => null;
+const store = x => () => x;
 
 module.exports = { store };

Exercises/3-wrapper.js

@@ -1,5 +1,22 @@
 'use strict';
 
-const contract = (fn, ...types) => null;
+const contract = (fn, ...types) => (...args) => {
+
+  for (let i = 0; i < types.length - 1; i++) {
+    const arg = args[i];
+    const curType = types[i].name.toLowerCase();
+
+    if (typeof arg !== curType) {
+      throw TypeError(`argument ${args[i]} is not a ${types[i].name}`);
+    }
+  }
+
+  const result = fn(...args);
+  const resultType = types[types.length - 1].name.toLowerCase();
+  if (typeof result !== resultType) {
+    throw TypeError(`result ${result} is not a ${resultType}`);
+  }
+  return result;
+};
 
 module.exports = { contract };

JavaScript/1-math.js

@@ -1,7 +1,6 @@
 'use strict';
 
-const { sin } = Math;
-const π = Math.PI;
+const { sin, PI: π } = Math;
 
 const inverse = f => x => 1 / f(x);