Lazy structures, structure is no longer iterable, removed copy on read-only buffers.

README.md

@@ -58,11 +58,11 @@ repositories {
 
 Then use regular dependency like
 ```groovy
-compile(group: 'scientifik', name: 'kmath-core-jvm', version: '0.0.1-SNAPSHOT')
+compile(group: 'scientifik', name: 'kmath-core', version: '0.0.1-SNAPSHOT')
 ```
 or in kotlin
 ```kotlin
-compile(group = "scientifik", name = "kmath-core-jvm", version = "0.0.1-SNAPSHOT")
+compile(group = "scientifik", name = "kmath-core", version = "0.0.1-SNAPSHOT")
 ```
 
 Work builds could be obtained with [![](https://jitpack.io/v/altavir/kmath.svg)](https://jitpack.io/#altavir/kmath). 

build.gradle.kts

@@ -1,7 +1,11 @@
 buildscript {
-    extra["kotlinVersion"] = "1.3.10"
+    extra["kotlinVersion"] = "1.3.11"
+    extra["ioVersion"] = "0.1.2-dev-2"
+    extra["coroutinesVersion"] = "1.0.1"
 
     val kotlinVersion: String by extra
+    val ioVersion: String by extra
+    val coroutinesVersion: String by extra
 
     repositories {
         jcenter()
@@ -15,6 +19,7 @@ buildscript {
 
 plugins {
     id("com.jfrog.artifactory") version "4.8.1"  apply false
+//    id("org.jetbrains.kotlin.multiplatform") apply false
 }
 
 allprojects {
@@ -22,7 +27,7 @@ allprojects {
     apply(plugin = "com.jfrog.artifactory")
 
     group = "scientifik"
-    version = "0.0.1-SNAPSHOT"
+    version = "0.0.2-dev-1"
 }
 
 if(file("artifactory.gradle").exists()){

kmath-core/build.gradle

@@ -1,5 +1,5 @@
 plugins {
-    id 'kotlin-multiplatform'
+    id "org.jetbrains.kotlin.multiplatform"
 }
 
 kotlin {
@@ -14,7 +14,7 @@ kotlin {
     sourceSets {
         commonMain {
             dependencies {
-                implementation 'org.jetbrains.kotlin:kotlin-stdlib-common'
+                api 'org.jetbrains.kotlin:kotlin-stdlib-common'
             }
         }
         commonTest {
@@ -25,7 +25,7 @@ kotlin {
         }
         jvmMain {
             dependencies {
-                implementation 'org.jetbrains.kotlin:kotlin-stdlib-jdk8'
+                api 'org.jetbrains.kotlin:kotlin-stdlib-jdk8'
             }
         }
         jvmTest {
@@ -36,7 +36,7 @@ kotlin {
         }
         jsMain {
             dependencies {
-                implementation 'org.jetbrains.kotlin:kotlin-stdlib-js'
+                api 'org.jetbrains.kotlin:kotlin-stdlib-js'
             }
         }
         jsTest {

kmath-core/src/commonMain/kotlin/scientifik/kmath/histogram/FastHistogram.kt

@@ -85,7 +85,7 @@ class FastHistogram(
         values[index].increment()
     }
 
-    override fun iterator(): Iterator<PhantomBin<Double>> = values.asSequence().map { (index, value) ->
+    override fun iterator(): Iterator<PhantomBin<Double>> = values.elements().map { (index, value) ->
         PhantomBin(getTemplate(index), value.sum())
     }.iterator()
 
@@ -100,7 +100,7 @@ class FastHistogram(
      * Create a phantom lightweight immutable copy of this histogram
      */
     fun asPhantomHistogram(): PhantomHistogram<Double> {
-        val binTemplates = values.associate { (index, _) -> getTemplate(index) to index }
+        val binTemplates = values.elements().associate { (index, _) -> getTemplate(index) to index }
         return PhantomHistogram(binTemplates, asNDStructure())
     }
 

kmath-core/src/commonMain/kotlin/scientifik/kmath/linear/Vector.kt

@@ -98,8 +98,6 @@ class ArrayVector<T : Any, F : Field<T>> internal constructor(override val conte
 
     override fun iterator(): Iterator<T> = (0 until size).map { element[it] }.iterator()
 
-    override fun copy(): ArrayVector<T, F> = ArrayVector(context, element)
-
     override fun toString(): String = this.joinToString(prefix = "[", postfix = "]", separator = ", ") { it.toString() }
 }
 

kmath-core/src/commonMain/kotlin/scientifik/kmath/operations/Complex.kt

@@ -38,4 +38,8 @@ data class Complex(val re: Double, val im: Double) : FieldElement<Complex, Compl
     val abs: Double
         get() = kotlin.math.sqrt(square)
 
+    companion object {
+
+    }
+
 }

kmath-core/src/commonMain/kotlin/scientifik/kmath/operations/Fields.kt

@@ -49,6 +49,9 @@ inline class Real(val value: Double) : FieldElement<Real, RealField> {
     override val context
         get() = RealField
 
+    companion object {
+
+    }
 }
 
 /**
@@ -72,3 +75,15 @@ object DoubleField : ExtendedField<Double>, Norm<Double, Double> {
 
     override fun norm(arg: Double): Double = kotlin.math.abs(arg)
 }
+
+/**
+ * A field for double without boxing. Does not produce appropriate field element
+ */
+object IntField : Field<Int>{
+    override val zero: Int = 0
+    override fun add(a: Int, b: Int): Int = a + b
+    override fun multiply(a: Int, b: Int): Int = a * b
+    override fun multiply(a: Int, k: Double): Int = (k*a).toInt()
+    override val one: Int = 1
+    override fun divide(a: Int, b: Int): Int = a / b
+}

kmath-core/src/commonMain/kotlin/scientifik/kmath/structures/Buffers.kt

@@ -11,11 +11,6 @@ interface Buffer<T> {
     operator fun get(index: Int): T
 
     operator fun iterator(): Iterator<T>
-
-    /**
-     * A shallow copy of the buffer
-     */
-    fun copy(): Buffer<T>
 }
 
 fun <T> Buffer<T>.asSequence(): Sequence<T> = iterator().asSequence()
@@ -26,7 +21,7 @@ interface MutableBuffer<T> : Buffer<T> {
     /**
      * A shallow copy of the buffer
      */
-    override fun copy(): MutableBuffer<T>
+    fun copy(): MutableBuffer<T>
 }
 
 
@@ -38,8 +33,6 @@ inline class ListBuffer<T>(private val list: List<T>) : Buffer<T> {
     override fun get(index: Int): T = list[index]
 
     override fun iterator(): Iterator<T> = list.iterator()
-
-    override fun copy(): ListBuffer<T> = ListBuffer(ArrayList(list))
 }
 
 inline class MutableListBuffer<T>(private val list: MutableList<T>) : MutableBuffer<T> {
@@ -104,10 +97,43 @@ inline class IntBuffer(private val array: IntArray): MutableBuffer<Int>{
     override fun copy(): MutableBuffer<Int> = IntBuffer(array.copyOf())
 }
 
-inline fun <reified T : Any> buffer(size: Int, noinline initializer: (Int) -> T): Buffer<T> {
+inline class ReadOnlyBuffer<T>(private val buffer: MutableBuffer<T>) : Buffer<T> {
-    return ArrayBuffer(Array(size, initializer))
+    override val size: Int get() = buffer.size
+
+    override fun get(index: Int): T = buffer.get(index)
+
+    override fun iterator(): Iterator<T> = buffer.iterator()
 }
 
-inline fun <reified T : Any> mutableBuffer(size: Int, noinline initializer: (Int) -> T): MutableBuffer<T> {
+/**
-    return ArrayBuffer(Array(size, initializer))
+ * Convert this buffer to read-only buffer
+ */
+fun <T> Buffer<T>.asReadOnly(): Buffer<T> = if (this is MutableBuffer) {
+    ReadOnlyBuffer(this)
+} else {
+    this
+}
+
+/**
+ * Create most appropriate immutable buffer for given type avoiding boxing wherever possible
+ */
+@Suppress("UNCHECKED_CAST")
+inline fun <reified T : Any> buffer(size: Int, noinline initializer: (Int) -> T): Buffer<T> {
+    return when (T::class) {
+        Double::class -> DoubleBuffer(DoubleArray(size) { initializer(it) as Double }) as Buffer<T>
+        Int::class -> IntBuffer(IntArray(size) { initializer(it) as Int }) as Buffer<T>
+        else -> ArrayBuffer(Array(size, initializer))
+    }
+}
+
+/**
+ * Create most appropriate mutable buffer for given type avoiding boxing wherever possible
+ */
+@Suppress("UNCHECKED_CAST")
+inline fun <reified T : Any> mutableBuffer(size: Int, noinline initializer: (Int) -> T): MutableBuffer<T> {
+    return when (T::class) {
+        Double::class -> DoubleBuffer(DoubleArray(size) { initializer(it) as Double }) as MutableBuffer<T>
+        Int::class -> IntBuffer(IntArray(size) { initializer(it) as Int }) as MutableBuffer<T>
+        else -> ArrayBuffer(Array(size, initializer))
+    }
 }

kmath-core/src/commonMain/kotlin/scientifik/kmath/structures/NDField.kt

@@ -23,7 +23,7 @@ abstract class NDField<T, F : Field<T>>(val shape: IntArray, val field: F) : Fie
      * Create new instance of NDArray using field shape and given initializer
      * The producer takes list of indices as argument and returns contained value
      */
-    fun produce(initializer: F.(IntArray) -> T): NDElement<T, F> = NDElement(this, produceStructure(initializer))
+    fun produce(initializer: F.(IntArray) -> T): NDElement<T, F> = NDStructureElement(this, produceStructure(initializer))
 
     override val zero: NDElement<T, F> by lazy {
         produce { zero }
@@ -83,7 +83,7 @@ abstract class NDField<T, F : Field<T>>(val shape: IntArray, val field: F) : Fie
 //    /**
 //     * Reverse minus operation
 //     */
-//    operator fun T.minus(arg: NDElement<T, F>): NDElement<T, F> = arg.transform { _, value ->
+//    operator fun T.minus(arg: NDElement<T, F>): NDElement<T, F> = arg.transformIndexed { _, value ->
 //        with(arg.context.field) {
 //            this@minus - value
 //        }
@@ -97,38 +97,41 @@ abstract class NDField<T, F : Field<T>>(val shape: IntArray, val field: F) : Fie
 //    /**
 //     * Reverse division operation
 //     */
-//    operator fun T.div(arg: NDElement<T, F>): NDElement<T, F> = arg.transform { _, value ->
+//    operator fun T.div(arg: NDElement<T, F>): NDElement<T, F> = arg.transformIndexed { _, value ->
 //        with(arg.context.field) {
 //            this@div / value
 //        }
 //    }
 }
 
+
+interface NDElement<T, F : Field<T>>: FieldElement<NDElement<T, F>, NDField<T, F>>, NDStructure<T>
+
+inline fun <T, F : Field<T>> NDElement<T, F>.transformIndexed(crossinline action: F.(IntArray, T) -> T): NDElement<T, F> = context.produce { action(it, get(*it)) }
+inline fun <T, F : Field<T>> NDElement<T, F>.transform(crossinline action: F.(T) -> T): NDElement<T, F> = context.produce { action(get(*it)) }
+
+
 /**
- *  Immutable [NDStructure] coupled to the context. Emulates Python ndarray
+ *  Read-only [NDStructure] coupled to the context.
  */
-class NDElement<T, F : Field<T>>(override val context: NDField<T, F>, private val structure: NDStructure<T>) : FieldElement<NDElement<T, F>, NDField<T, F>>, NDStructure<T> by structure {
+class NDStructureElement<T, F : Field<T>>(override val context: NDField<T, F>, private val structure: NDStructure<T>) : NDElement<T,F>, NDStructure<T> by structure {
 
     //TODO ensure structure is immutable
 
-    override val self: NDElement<T, F>
+    override val self: NDElement<T, F>  get() = this
-        get() = this
-
-    inline fun transform(crossinline action: (IntArray, T) -> T): NDElement<T, F> = context.produce { action(it, get(*it)) }
-    inline fun transform(crossinline action: (T) -> T): NDElement<T, F> = context.produce { action(get(*it)) }
 }
 
 /**
  * Element by element application of any operation on elements to the whole array. Just like in numpy
  */
-operator fun <T, F : Field<T>> Function1<T, T>.invoke(ndElement: NDElement<T, F>): NDElement<T, F> = ndElement.transform { _, value -> this(value) }
+operator fun <T, F : Field<T>> Function1<T, T>.invoke(ndElement: NDElement<T, F>): NDElement<T, F> = ndElement.transform {value -> this@invoke(value) }
 
 /* plus and minus */
 
 /**
  * Summation operation for [NDElement] and single element
  */
-operator fun <T, F : Field<T>> NDElement<T, F>.plus(arg: T): NDElement<T, F> = transform { _, value ->
+operator fun <T, F : Field<T>> NDElement<T, F>.plus(arg: T): NDElement<T, F> = transform {value ->
     with(context.field) {
         arg + value
     }
@@ -137,7 +140,7 @@ operator fun <T, F : Field<T>> NDElement<T, F>.plus(arg: T): NDElement<T, F> = t
 /**
  * Subtraction operation between [NDElement] and single element
  */
-operator fun <T, F : Field<T>> NDElement<T, F>.minus(arg: T): NDElement<T, F> = transform { _, value ->
+operator fun <T, F : Field<T>> NDElement<T, F>.minus(arg: T): NDElement<T, F> = transform {value ->
     with(context.field) {
         arg - value
     }
@@ -148,7 +151,7 @@ operator fun <T, F : Field<T>> NDElement<T, F>.minus(arg: T): NDElement<T, F> =
 /**
  * Product operation for [NDElement] and single element
  */
-operator fun <T, F : Field<T>> NDElement<T, F>.times(arg: T): NDElement<T, F> = transform { _, value ->
+operator fun <T, F : Field<T>> NDElement<T, F>.times(arg: T): NDElement<T, F> = transform { value ->
     with(context.field) {
         arg * value
     }
@@ -157,7 +160,7 @@ operator fun <T, F : Field<T>> NDElement<T, F>.times(arg: T): NDElement<T, F> =
 /**
  * Division operation between [NDElement] and single element
  */
-operator fun <T, F : Field<T>> NDElement<T, F>.div(arg: T): NDElement<T, F> = transform { _, value ->
+operator fun <T, F : Field<T>> NDElement<T, F>.div(arg: T): NDElement<T, F> = transform { value ->
     with(context.field) {
         arg / value
     }

kmath-core/src/commonMain/kotlin/scientifik/kmath/structures/NDStructure.kt

@@ -1,7 +1,7 @@
 package scientifik.kmath.structures
 
 
-interface NDStructure<T> : Iterable<Pair<IntArray, T>> {
+interface NDStructure<T> {
 
     val shape: IntArray
 
@@ -9,6 +9,8 @@ interface NDStructure<T> : Iterable<Pair<IntArray, T>> {
         get() = shape.size
 
     operator fun get(index: IntArray): T
+
+    fun elements(): Sequence<Pair<IntArray, T>>
 }
 
 operator fun <T> NDStructure<T>.get(vararg index: Int): T = get(index)
@@ -18,7 +20,7 @@ interface MutableNDStructure<T> : NDStructure<T> {
 }
 
 fun <T> MutableNDStructure<T>.transformInPlace(action: (IntArray, T) -> T) {
-    for ((index, oldValue) in this) {
+    elements().forEach { (index, oldValue) ->
         this[index] = action(index, oldValue)
     }
 }
@@ -107,8 +109,8 @@ abstract class GenericNDStructure<T, B : Buffer<T>> : NDStructure<T> {
     override val shape: IntArray
         get() = strides.shape
 
-    override fun iterator(): Iterator<Pair<IntArray, T>> =
+    override fun elements()=
-            strides.indices().map { it to this[it] }.iterator()
+            strides.indices().map { it to this[it] }
 }
 
 /**
@@ -169,6 +171,6 @@ fun <T> genericNdStructure(shape: IntArray, initializer: (IntArray) -> T): Mutab
             yield(initializer(it))
         }
     }
-    val buffer = MutableListBuffer<T>(sequence.toMutableList())
+    val buffer = MutableListBuffer(sequence.toMutableList())
     return MutableBufferNDStructure(strides, buffer)
 }

kmath-core/src/jvmMain/kotlin/scientifik/kmath/structures/BufferSpec.kt

@@ -0,0 +1,55 @@
+package scientifik.kmath.structures
+
+import java.nio.ByteBuffer
+
+
+/**
+ * A specification for serialization and deserialization objects to buffer
+ */
+interface BufferSpec<T : Any> {
+    fun fromBuffer(buffer: ByteBuffer): T
+    fun toBuffer(value: T): ByteBuffer
+}
+
+/**
+ * A [BufferSpec] with fixed unit size. Allows storage of any object without boxing.
+ */
+interface FixedSizeBufferSpec<T : Any> : BufferSpec<T> {
+    val unitSize: Int
+
+    /**
+     * Read an object from buffer in current position
+     */
+    fun ByteBuffer.readObject(): T {
+        val buffer = ByteArray(unitSize)
+        get(buffer)
+        return fromBuffer(ByteBuffer.wrap(buffer))
+    }
+
+    /**
+     * Read an object from buffer in given index (not buffer position
+     */
+    fun ByteBuffer.readObject(index: Int): T {
+        val dup = duplicate()
+        dup.position(index*unitSize)
+        return dup.readObject()
+    }
+
+    /**
+     * Write object to [ByteBuffer] in current buffer position
+     */
+    fun ByteBuffer.writeObject(obj: T) {
+        val buffer = toBuffer(obj).apply { rewind() }
+        assert(buffer.limit() == unitSize)
+        put(buffer)
+    }
+
+    /**
+     * Put an object in given index
+     */
+    fun ByteBuffer.writeObject(index: Int, obj: T) {
+        val dup = duplicate()
+        dup.position(index*unitSize)
+        dup.writeObject(obj)
+    }
+}

kmath-core/src/jvmMain/kotlin/scientifik/kmath/structures/ComplexBufferSpec.kt

@@ -0,0 +1,25 @@
+package scientifik.kmath.structures
+
+import scientifik.kmath.operations.Complex
+import java.nio.ByteBuffer
+
+object ComplexBufferSpec : FixedSizeBufferSpec<Complex> {
+    override val unitSize: Int = 16
+
+    override fun fromBuffer(buffer: ByteBuffer): Complex {
+        val re = buffer.getDouble(0)
+        val im = buffer.getDouble(8)
+        return Complex(re, im)
+    }
+
+    override fun toBuffer(value: Complex): ByteBuffer = ByteBuffer.allocate(16).apply {
+        putDouble(value.re)
+        putDouble(value.im)
+    }
+}
+
+/**
+ * Create a mutable buffer which ignores boxing
+ */
+fun Complex.Companion.createBuffer(size: Int) = ObjectBuffer.create(ComplexBufferSpec, size)
+

kmath-core/src/jvmMain/kotlin/scientifik/kmath/structures/ObjectBuffer.kt

@@ -0,0 +1,28 @@
+package scientifik.kmath.structures
+
+import java.nio.ByteBuffer
+
+class ObjectBuffer<T : Any>(private val buffer: ByteBuffer, private val spec: FixedSizeBufferSpec<T>) : MutableBuffer<T> {
+    override val size: Int
+        get() = buffer.limit() / spec.unitSize
+
+    override fun get(index: Int): T = with(spec) { buffer.readObject(index) }
+
+    override fun iterator(): Iterator<T> = (0 until size).asSequence().map { get(it) }.iterator()
+
+    override fun set(index: Int, value: T) = with(spec) { buffer.writeObject(index, value) }
+
+    override fun copy(): MutableBuffer<T> {
+        val dup = buffer.duplicate()
+        val copy = ByteBuffer.allocate(dup.capacity())
+        dup.rewind()
+        copy.put(dup)
+        copy.flip()
+        return ObjectBuffer(copy, spec)
+    }
+
+    companion object {
+        fun <T : Any> create(spec: FixedSizeBufferSpec<T>, size: Int) =
+                ObjectBuffer<T>(ByteBuffer.allocate(size * spec.unitSize), spec)
+    }
+}

kmath-core/src/jvmMain/kotlin/scientifik/kmath/structures/RealBufferSpec.kt

@@ -0,0 +1,23 @@
+package scientifik.kmath.structures
+
+import scientifik.kmath.operations.Real
+import java.nio.ByteBuffer
+
+object RealBufferSpec : FixedSizeBufferSpec<Real> {
+    override val unitSize: Int = 8
+
+    override fun fromBuffer(buffer: ByteBuffer): Real = Real(buffer.double)
+
+    override fun toBuffer(value: Real): ByteBuffer = ByteBuffer.allocate(8).apply { putDouble(value.value) }
+}
+
+object DoubleBufferSpec : FixedSizeBufferSpec<Double> {
+    override val unitSize: Int = 8
+
+    override fun fromBuffer(buffer: ByteBuffer): Double = buffer.double
+
+    override fun toBuffer(value: Double): ByteBuffer = ByteBuffer.allocate(8).apply { putDouble(value) }
+}
+
+fun Double.Companion.createBuffer(size: Int) = ObjectBuffer.create(DoubleBufferSpec, size)
+fun Real.Companion.createBuffer(size: Int) = ObjectBuffer.create(RealBufferSpec, size)

kmath-core/src/jvmTest/kotlin/scientifik/kmath/structures/ComplexBufferSpecTest.kt

@@ -0,0 +1,17 @@
+package scientifik.kmath.structures
+
+import org.junit.Test
+import scientifik.kmath.operations.Complex
+import kotlin.test.assertEquals
+
+class ComplexBufferSpecTest {
+    @Test
+    fun testComplexBuffer() {
+        val buffer = Complex.createBuffer(20)
+        (0 until 20).forEach {
+            buffer[it] = Complex(it.toDouble(), -it.toDouble())
+        }
+
+        assertEquals(Complex(5.0, -5.0), buffer[5])
+    }
+}

kmath-coroutines/build.gradle

@@ -0,0 +1,42 @@
+plugins {
+    id "org.jetbrains.kotlin.multiplatform"
+}
+
+kotlin {
+    targets {
+        fromPreset(presets.jvm, 'jvm')
+        // For ARM, preset should be changed to presets.iosArm32 or presets.iosArm64
+        // For Linux, preset should be changed to e.g. presets.linuxX64
+        // For MacOS, preset should be changed to e.g. presets.macosX64
+        //fromPreset(presets.mingwX64, 'mingw')
+    }
+    sourceSets {
+        commonMain {
+            dependencies {
+                api project(":kmath-core")
+                api "org.jetbrains.kotlinx:kotlinx-coroutines-core-common:$coroutinesVersion"
+            }
+        }
+        commonTest {
+            dependencies {
+                api 'org.jetbrains.kotlin:kotlin-test-common'
+                api 'org.jetbrains.kotlin:kotlin-test-annotations-common'
+            }
+        }
+        jvmMain {
+            dependencies {
+                api "org.jetbrains.kotlinx:kotlinx-coroutines-core:$coroutinesVersion"
+            }
+        }
+        jvmTest {
+            dependencies {
+                implementation 'org.jetbrains.kotlin:kotlin-test'
+                implementation 'org.jetbrains.kotlin:kotlin-test-junit'
+            }
+        }
+//        mingwMain {
+//        }
+//        mingwTest {
+//        }
+    }
+}

kmath-coroutines/src/commonMain/kotlin/scientifik/kmath/structures/CoroutinesExtra.kt

@@ -0,0 +1,11 @@
+package scientifik.kmath.structures
+
+import kotlinx.coroutines.CoroutineDispatcher
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
+import kotlin.coroutines.CoroutineContext
+import kotlin.coroutines.EmptyCoroutineContext
+
+expect fun <R> runBlocking(context: CoroutineContext = EmptyCoroutineContext, function: suspend CoroutineScope.()->R): R
+
+val Dispatchers.Math: CoroutineDispatcher get() = Dispatchers.Default

kmath-coroutines/src/commonMain/kotlin/scientifik/kmath/structures/LazyNDField.kt

@@ -0,0 +1,79 @@
+package scientifik.kmath.structures
+
+import kotlinx.coroutines.*
+import scientifik.kmath.operations.Field
+
+class LazyNDField<T, F : Field<T>>(shape: IntArray, field: F, val scope: CoroutineScope = GlobalScope) : NDField<T, F>(shape, field) {
+
+    override fun produceStructure(initializer: F.(IntArray) -> T): NDStructure<T> = LazyNDStructure(this) { initializer(field, it) }
+
+
+    override fun add(a: NDElement<T, F>, b: NDElement<T, F>): NDElement<T, F> {
+        return LazyNDStructure(this) { index ->
+            val aDeferred = a.deferred(index)
+            val bDeferred = b.deferred(index)
+            aDeferred.await() + bDeferred.await()
+        }
+    }
+
+    override fun multiply(a: NDElement<T, F>, k: Double): NDElement<T, F> {
+        return LazyNDStructure(this) { index -> a.await(index) * k }
+    }
+
+    override fun multiply(a: NDElement<T, F>, b: NDElement<T, F>): NDElement<T, F> {
+        return LazyNDStructure(this) { index ->
+            val aDeferred = a.deferred(index)
+            val bDeferred = b.deferred(index)
+            aDeferred.await() * bDeferred.await()
+        }
+    }
+
+    override fun divide(a: NDElement<T, F>, b: NDElement<T, F>): NDElement<T, F> {
+        return LazyNDStructure(this) { index ->
+            val aDeferred = a.deferred(index)
+            val bDeferred = b.deferred(index)
+            aDeferred.await() / bDeferred.await()
+        }
+    }
+}
+
+class LazyNDStructure<T, F : Field<T>>(override val context: LazyNDField<T, F>, val function: suspend F.(IntArray) -> T) : NDElement<T, F>, NDStructure<T> {
+    override val self: NDElement<T, F> get() = this
+    override val shape: IntArray get() = context.shape
+
+    private val cache = HashMap<IntArray, Deferred<T>>()
+
+    fun deferred(index: IntArray) = cache.getOrPut(index) { context.scope.async(context = Dispatchers.Math) { function.invoke(context.field, index) } }
+
+    suspend fun await(index: IntArray): T = deferred(index).await()
+
+    override fun get(index: IntArray): T = runBlocking {
+        deferred(index).await()
+    }
+
+    override fun elements(): Sequence<Pair<IntArray, T>> {
+        val strides = DefaultStrides(shape)
+        return strides.indices().map { index -> index to runBlocking { await(index) } }
+    }
+}
+
+fun <T> NDElement<T, *>.deferred(index: IntArray) = if (this is LazyNDStructure<T, *>) this.deferred(index) else CompletableDeferred(get(index))
+
+suspend fun <T> NDElement<T, *>.await(index: IntArray) = if (this is LazyNDStructure<T, *>) this.await(index) else get(index)
+
+fun <T, F : Field<T>> NDElement<T, F>.lazy(scope: CoroutineScope = GlobalScope): LazyNDStructure<T, F> {
+    return if (this is LazyNDStructure<T, F>) {
+        this
+    } else {
+        val context = LazyNDField(context.shape, context.field)
+        LazyNDStructure(context) { get(it) }
+    }
+}
+
+inline fun <T, F : Field<T>> LazyNDStructure<T, F>.transformIndexed(crossinline action: suspend F.(IntArray, T) -> T) = LazyNDStructure(context) { index ->
+    action.invoke(this, index, await(index))
+}
+
+inline fun <T, F : Field<T>> LazyNDStructure<T, F>.transform(crossinline action: suspend F.(T) -> T) = LazyNDStructure(context) { index ->
+    action.invoke(this, await(index))
+}

kmath-coroutines/src/commonTest/kotlin/scientifik/kmath/structures/LazyNDFieldTest.kt

@@ -0,0 +1,20 @@
+package scientifik.kmath.structures
+
+import scientifik.kmath.operations.IntField
+import kotlin.test.Test
+import kotlin.test.assertEquals
+
+
+class LazyNDFieldTest {
+    @Test
+    fun testLazyStructure() {
+        var counter = 0
+        val regularStructure = NDArrays.create(IntField, intArrayOf(2, 2, 2)) { it[0] + it[1] - it[2] }
+        val result = (regularStructure.lazy() + 2).transform {
+            counter++
+            it * it
+        }
+        assertEquals(4, result[0,0,0])
+        assertEquals(1, counter)
+    }
+}

kmath-coroutines/src/jvmMain/kotlin/scientifik/kmath/structures/_CoroutinesExtra.kt

@@ -0,0 +1,6 @@
+package scientifik.kmath.structures
+
+import kotlinx.coroutines.CoroutineScope
+import kotlin.coroutines.CoroutineContext
+
+actual fun <R> runBlocking(context: CoroutineContext, function: suspend CoroutineScope.() -> R): R  = kotlinx.coroutines.runBlocking(context, function)

kmath-io/build.gradle

@@ -1,5 +1,5 @@
 plugins {
-    id 'kotlin-multiplatform'
+    id "org.jetbrains.kotlin.multiplatform"
 }
 
 kotlin {
@@ -16,6 +16,7 @@ kotlin {
             dependencies {
                 api project(":kmath-core")
                 implementation 'org.jetbrains.kotlin:kotlin-stdlib-common'
+                api "org.jetbrains.kotlinx:kotlinx-io:$ioVersion"
             }
         }
         commonTest {
@@ -27,6 +28,7 @@ kotlin {
         jvmMain {
             dependencies {
                 implementation 'org.jetbrains.kotlin:kotlin-stdlib-jdk8'
+                api "org.jetbrains.kotlinx:kotlinx-io-jvm:$ioVersion"
             }
         }
         jvmTest {

kmath-jmh/build.gradle

@@ -5,6 +5,6 @@ plugins {
 }
 
 dependencies {
-    implementation project(':kmath-core')
+    compile project(':kmath-core')
-    jmh 'org.jetbrains.kotlin:kotlin-stdlib-jdk8'
+    //jmh project(':kmath-core')
 }

kmath-jmh/src/jmh/kotlin/scientifik/kmath/structures/ArrayBenchmark.kt

@@ -4,8 +4,7 @@ import org.openjdk.jmh.annotations.*
 import java.nio.IntBuffer
 
 
-@Fork(1)
+@Warmup(iterations = 1)
-@Warmup(iterations = 2)
 @Measurement(iterations = 5)
 @State(Scope.Benchmark)
 open class ArrayBenchmark {
@@ -30,7 +29,6 @@ open class ArrayBenchmark {
         for (i in 1..10000) {
             res += array[10000 - i]
         }
-        print(res)
     }
 
     @Benchmark
@@ -39,7 +37,6 @@ open class ArrayBenchmark {
         for (i in 1..10000) {
             res += arrayBuffer.get(10000 - i)
         }
-        print(res)
     }
 
     @Benchmark
@@ -48,6 +45,5 @@ open class ArrayBenchmark {
         for (i in 1..10000) {
             res += nativeBuffer.get(10000 - i)
         }
-        print(res)
     }
 }

kmath-jmh/src/jmh/kotlin/scientifik/kmath/structures/BufferBenchmark.kt

@@ -0,0 +1,38 @@
+package scientifik.kmath.structures
+
+import org.openjdk.jmh.annotations.*
+import scientifik.kmath.operations.Complex
+
+@Warmup(iterations = 1)
+@Measurement(iterations = 5)
+@State(Scope.Benchmark)
+open class BufferBenchmark {
+
+    @Benchmark
+    fun genericDoubleBufferReadWrite() {
+        val buffer = Double.createBuffer(size)
+        (0 until size).forEach {
+            buffer[it] = it.toDouble()
+        }
+
+        (0 until size).forEach {
+            buffer[it]
+        }
+    }
+
+    @Benchmark
+    fun complexBufferReadWrite() {
+        val buffer = Complex.createBuffer(size/2)
+        (0 until size/2).forEach {
+            buffer[it] = Complex(it.toDouble(), -it.toDouble())
+        }
+
+        (0 until size/2).forEach {
+            buffer[it]
+        }
+    }
+
+    companion object {
+        const val size = 1000
+    }
+}

settings.gradle.kts

@@ -5,10 +5,12 @@ pluginManagement {
     }
 }
 
-enableFeaturePreview("GRADLE_METADATA")
+//enableFeaturePreview("GRADLE_METADATA")
 
 rootProject.name = "kmath"
 include(
         ":kmath-core",
+        ":kmath-io",
+        ":kmath-coroutines",
         ":kmath-jmh"
 )