diff --git a/src/main/kotlin/it/norangeb/algorithms/datastructures/bag/Bag.kt b/src/main/kotlin/it/norangeb/algorithms/datastructures/bag/Bag.kt
new file mode 100644
index 0000000..d21a7e4
--- /dev/null
+++ b/src/main/kotlin/it/norangeb/algorithms/datastructures/bag/Bag.kt
@@ -0,0 +1,35 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2019 norangebit
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ *
+ */
+
+package it.norangeb.algorithms.datastructures.bag
+
+interface Bag<T> {
+    fun add(elem: T)
+    fun size(): Int
+    fun isEmpty(): Boolean
+    fun clear()
+    fun <A> map(transform: (T) -> A): Bag<A>
+    fun forEach(action: (T) -> Unit)
+}
\ No newline at end of file
diff --git a/src/main/kotlin/it/norangeb/algorithms/datastructures/bag/LinkedListBag.kt b/src/main/kotlin/it/norangeb/algorithms/datastructures/bag/LinkedListBag.kt
new file mode 100644
index 0000000..630e557
--- /dev/null
+++ b/src/main/kotlin/it/norangeb/algorithms/datastructures/bag/LinkedListBag.kt
@@ -0,0 +1,82 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2019 norangebit
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ *
+ */
+
+package it.norangeb.algorithms.datastructures.bag
+
+import arrow.core.None
+import arrow.core.Option
+import arrow.core.Some
+import arrow.core.toOption
+
+class LinkedListBag<T>() : Bag<T> {
+    data class Node<A>(val value: A, val next: Option<Node<A>> = None)
+
+    private var head: Option<Node<T>> = None
+    private var size = 0
+
+    override fun add(elem: T) {
+        val node = Node(elem, head).toOption()
+        head = node
+        size++
+    }
+
+    override fun size(): Int = size
+
+    override fun isEmpty(): Boolean = size == 0
+
+    override fun clear() {
+        head = None
+        size = 0
+    }
+
+    override fun <A> map(transform: (T) -> A): Bag<A> {
+        var newCurrent: Option<Node<A>> = None
+        var oldCurrent = head
+
+        while (oldCurrent is Some) {
+            val node = Node(transform(oldCurrent.t.value), newCurrent)
+                .toOption()
+
+            newCurrent = node
+            oldCurrent = oldCurrent.t.next
+        }
+
+        return LinkedListBag(newCurrent, size)
+    }
+
+    private constructor(head: Option<Node<T>>, size: Int) : this() {
+        this.head = head
+        this.size = size
+    }
+
+    override fun forEach(action: (T) -> Unit) {
+        var current = head
+
+        while (current is Some) {
+            action(current.t.value)
+            current = current.t.next
+        }
+    }
+}
\ No newline at end of file
diff --git a/src/main/kotlin/it/norangeb/algorithms/datastructures/bag/ResizingArrayBag.kt b/src/main/kotlin/it/norangeb/algorithms/datastructures/bag/ResizingArrayBag.kt
new file mode 100644
index 0000000..c6d3688
--- /dev/null
+++ b/src/main/kotlin/it/norangeb/algorithms/datastructures/bag/ResizingArrayBag.kt
@@ -0,0 +1,80 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2019 norangebit
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ *
+ */
+
+package it.norangeb.algorithms.datastructures.bag
+
+class ResizingArrayBag<T>(capacity: Int = DEFAULT_CAPACITY) : Bag<T> {
+    private var bag: Array<T?> = arrayOfNulls<Any?>(capacity) as Array<T?>
+    private var size = 0
+
+    override fun add(elem: T) {
+        if (isFull())
+            resizeArray(size * RESIZE_FACTOR)
+
+        bag[size++] = elem
+    }
+
+    private fun isFull(): Boolean = size == bag.size
+
+    private fun resizeArray(capacity: Int) {
+        bag = bag.copyOf(capacity)
+    }
+
+    override fun size(): Int = size
+
+    override fun isEmpty(): Boolean = size == 0
+
+    override fun <A> map(transform: (T) -> A): Bag<A> {
+        val newBag: Array<A?> = arrayOfNulls<Any?>(size) as Array<A?>
+
+        for (i in 0 until size) {
+            val elem = bag[i] ?: continue
+            newBag[i] = transform(elem)
+        }
+
+        return ResizingArrayBag(size, newBag)
+    }
+
+    private constructor(size: Int, bag: Array<T?>) : this() {
+        this.size = size
+        this.bag = bag
+    }
+
+    override fun forEach(action: (T) -> Unit) {
+        for (elem in bag)
+            if (elem != null)
+                action(elem)
+    }
+
+    override fun clear() {
+        size = 0
+        resizeArray(DEFAULT_CAPACITY)
+    }
+
+    companion object {
+        const val DEFAULT_CAPACITY = 2
+        const val RESIZE_FACTOR = 2
+    }
+}
\ No newline at end of file
diff --git a/src/test/kotlin/it/norangeb/algorithms/datastructures/bag/LinkedListBagTest.kt b/src/test/kotlin/it/norangeb/algorithms/datastructures/bag/LinkedListBagTest.kt
new file mode 100644
index 0000000..92856c3
--- /dev/null
+++ b/src/test/kotlin/it/norangeb/algorithms/datastructures/bag/LinkedListBagTest.kt
@@ -0,0 +1,95 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2019 norangebit
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ *
+ */
+
+package it.norangeb.algorithms.datastructures.bag
+
+import org.amshove.kluent.`should be equal to`
+import org.junit.Before
+import org.junit.jupiter.api.Test
+
+class LinkedListBagTest {
+    private var bag = LinkedListBag<Int>()
+
+    @Before
+    fun makeBag() {
+        bag = LinkedListBag()
+    }
+
+    @Test
+    fun testAdd() {
+        bag.size() `should be equal to` 0
+        bag.add(1)
+        bag.size() `should be equal to` 1
+        bag.add(1)
+        bag.size() `should be equal to` 2
+        bag.add(1)
+        bag.size() `should be equal to` 3
+    }
+
+    @Test
+    fun testIsEmpty() {
+        bag.isEmpty() `should be equal to` true
+        bag.add(1)
+        bag.isEmpty() `should be equal to` false
+    }
+
+    @Test
+    fun testMap() {
+        bag.add(1)
+        bag.add(2)
+        bag.add(3)
+        bag.add(4)
+        bag.add(5)
+
+        bag.map { it * 2 }.size() `should be equal to` 5
+    }
+
+    @Test
+    fun testForEach() {
+        bag.add(1)
+        bag.add(2)
+        bag.add(3)
+        bag.add(4)
+        bag.add(5)
+
+        var x = 0
+
+        bag.forEach { x++ }
+
+        x `should be equal to` 5
+    }
+
+    @Test
+    fun testClear() {
+        bag.add(1)
+        bag.add(2)
+        bag.add(3)
+        bag.add(4)
+        bag.add(5)
+        bag.clear()
+
+        bag.size() `should be equal to` 0
+    }
+}
\ No newline at end of file
diff --git a/src/test/kotlin/it/norangeb/algorithms/datastructures/bag/ResizingArrayBagTest.kt b/src/test/kotlin/it/norangeb/algorithms/datastructures/bag/ResizingArrayBagTest.kt
new file mode 100644
index 0000000..747cba9
--- /dev/null
+++ b/src/test/kotlin/it/norangeb/algorithms/datastructures/bag/ResizingArrayBagTest.kt
@@ -0,0 +1,95 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2019 norangebit
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ *
+ */
+
+package it.norangeb.algorithms.datastructures.bag
+
+import org.amshove.kluent.`should be equal to`
+import org.junit.Before
+import org.junit.jupiter.api.Test
+
+class ResizingArrayBagTest {
+    private var bag = ResizingArrayBag<Int>()
+
+    @Before
+    fun makeBag() {
+        bag = ResizingArrayBag()
+    }
+
+    @Test
+    fun testAdd() {
+        bag.size() `should be equal to` 0
+        bag.add(1)
+        bag.size() `should be equal to` 1
+        bag.add(1)
+        bag.size() `should be equal to` 2
+        bag.add(1)
+        bag.size() `should be equal to` 3
+    }
+
+    @Test
+    fun testIsEmpty() {
+        bag.isEmpty() `should be equal to` true
+        bag.add(1)
+        bag.isEmpty() `should be equal to` false
+    }
+
+    @Test
+    fun testMap() {
+        bag.add(1)
+        bag.add(2)
+        bag.add(3)
+        bag.add(4)
+        bag.add(5)
+
+        bag.map { it * 2 }.size() `should be equal to` 5
+    }
+
+    @Test
+    fun testForEach() {
+        bag.add(1)
+        bag.add(2)
+        bag.add(3)
+        bag.add(4)
+        bag.add(5)
+
+        var x = 0
+
+        bag.forEach { x++ }
+
+        x `should be equal to` 5
+    }
+
+    @Test
+    fun testClear() {
+        bag.add(1)
+        bag.add(2)
+        bag.add(3)
+        bag.add(4)
+        bag.add(5)
+        bag.clear()
+
+        bag.size() `should be equal to` 0
+    }
+}
\ No newline at end of file