adds fromArray

README.md

@@ -21,6 +21,8 @@ var person = {
     locationLens = objectLens('location'),
     numberLens = objectLens('number'),
     store = locationLens.andThen(numberLens).run(person);
+    // or
+    // store = Lens.fromArray(['location', 'number'])
 
 console.log(store.get());
 // 1006
@@ -50,6 +52,8 @@ var data = [{
     configLens = objectLens('config'),
     typeLens = objectLens('type'),
     configTypeLens = configLens.andThen(typeLens);
+    // or
+    // configTypeLens = Lens.fromArray(['config', 'type'])
 
 console.log(data.filter(function(o) {
     return configTypeLens.run(o).fold(

src/lens.js

@@ -49,4 +49,12 @@ Lens.arrayLens = function(index) {
     });
 };
 
+Lens.fromArray = function(props) {
+    return props.reduce((prev, next) =>
+        prev.andThen(
+            typeof next === 'string' ?  Lens.objectLens(next) : Lens.arrayLens(next)
+        ), Lens.id()
+    );
+};
+
 module.exports = Lens;

src/partial-lens.js

@@ -37,4 +37,12 @@ PartialLens.arrayLens = function(index) {
     });
 };
 
+PartialLens.fromArray = function(props) {
+    return props.reduce((prev, next) =>
+        prev.andThen(
+            typeof next === 'string'? PartialLens.objectLens(next) : PartialLens.arrayLens(next)
+        ), PartialLens.id()
+    );
+};
+
 module.exports = PartialLens;

test/test.js

@@ -78,6 +78,29 @@ exports.testUpdatePersonFirstSkill = function(test) {
     test.done();
 };
 
+exports.testUpdatePersonFirstSkillFromArray = function(test) {
+    var store = Lens.fromArray(['skills', 0]).run(person);
+
+    test.equal(store.get(), 'JavaScript');
+    test.deepEqual(
+        store.set('Haskell'),
+        {
+            name: 'Brian McKenna',
+            skills: [
+                'Haskell',
+                'Scala'
+            ],
+            location: {
+                number: 1006,
+                street: 'Pearl St',
+                postcode: 80302
+            }
+        }
+    );
+    test.done();
+};
+
+
 exports.testNestedFilter = function(test) {
     var config = PartialLens.objectLens('config'),
         type = PartialLens.objectLens('type'),
@@ -107,6 +130,33 @@ exports.testNestedFilter = function(test) {
     test.done();
 };
 
+exports.testNestedFilterFromArray = function(test) {
+    var configType = PartialLens.fromArray(['config', 'type']),
+        result = data.filter(function(d) {
+            return configType.run(d).fold(
+                function(store) {
+                    return store.get() == 2;
+                },
+                function() {
+                    return false;
+                }
+            );
+        });
+
+    test.deepEqual(
+        result,
+        [
+            {
+                name: 'First record',
+                config: {
+                    type: 2
+                }
+            }
+        ]
+    );
+    test.done();
+};
+
 exports.testValidation = function(test) {
     var Option = require('fantasy-options'),
         o = PartialLens.objectLens,