added matrix() function.

added a unit test.

Author: Muhammad Hashim

build.gradle

@@ -24,7 +24,8 @@ repositories {
 
 dependencies {
     compile "org.jetbrains.kotlin:kotlin-stdlib-jdk8:$kotlin_version"
-    testCompile group: 'junit', name: 'junit', version: '4.12'
+    testCompile "junit:junit:4.12"
+
 }
 
 compileKotlin {

src/main/kotlin/mhashim6/kotlin/arrays2d/2DArrayExtensions.kt

@@ -1,5 +1,9 @@
 package mhashim6.kotlin.arrays2d
 
+inline fun <reified T> matrix(row: Int, col: Int, noinline itemFactory: (i: Int, j: Int) -> T): Array<Array<T>> {
+    return Array(row) { i -> Array(col) { j -> itemFactory(i, j) } }
+}
+
 inline fun <T> Array<Array<T>>.forEach2D(action: (T) -> Unit) {
     for (array in this)
         for (item in array)

src/test/kotlin/Test.kt

@@ -0,0 +1,18 @@
+import mhashim6.kotlin.arrays2d.asSequence2D
+import mhashim6.kotlin.arrays2d.matrix
+import org.junit.Test
+
+class Test {
+
+    @Test
+    fun generalTest() {
+        var count = 0
+        val matrix = matrix(4, 4) { i, j -> Pair(i, j) }
+        matrix.asSequence2D()
+                .filter { it.second > 1 }
+                .forEach { count++ }
+
+        assert(count == 8)
+    }
+
+}