Add matchWith support

README.md

@@ -84,6 +84,13 @@ If `other` is not a function:
 * `some(value).valueOrElse(other)` returns `value`
 * `none.valueOrElse(other)` returns `other`
 
+### matchWith(*choices*)
+
+`choices` is an object of shape `{ Some: function, None: function }`.
+
+* `some(value).matchWith({ Some: funcA, None: funcB })` returns the result of `funcA(value)`
+* `none.matchWith({ Some: funcA, None: funcB })` returns the result of `funcB()`
+
 ## Functions
 
 ### option.isOption(*value*)

index.js

@@ -21,7 +21,10 @@ exports.none = Object.create({
         return [];
     },
     orElse: callOrReturn,
-    valueOrElse: callOrReturn
+    valueOrElse: callOrReturn,
+    matchWith: function(choices) {
+        return choices.None();
+    }
 });
 
 function callOrReturn(value) {
@@ -76,6 +79,10 @@ Some.prototype.valueOrElse = function(value) {
     return this._value;
 };
 
+Some.prototype.matchWith = function(choices) {
+  return choices.Some(this._value);
+};
+
 exports.isOption = function(value) {
     return value === exports.none || value instanceof Some;
 };

test/options.test.js

@@ -171,4 +171,20 @@ exports["when predicate(value) is false, some(value).filter(predicate) returns n
 
     test.deepEqual(some11.filter(equals3), options.none);
     test.done();
+};
+
+exports.noneMatchWithCallsFunctionUnderNoneKey = function(test) {
+  test.deepEqual(4, options.none.matchWith({
+    None: function() { return 4; },
+    Some: function(value) { return value; }
+  }));
+  test.done();
+};
+
+exports.someMatchWithCallsFunctionUnderSomeKeyPassingTheValue = function(test) {
+  test.deepEqual(12, options.some(11).matchWith({
+    None: function() { return 4; },
+    Some: function(value) { return value + 1 }
+  }));
+  test.done();
 };