and inlined at the use-site. Flexible: Using typeclass pattern, retroactively make types serializable NO BOILERPLATE: Typeclass instances generated at compile-time https://github.com/scala/pickling
and inlined at the use-site. Flexible: Using typeclass pattern, retroactively make types serializable NO BOILERPLATE: Typeclass instances generated at compile-time pluggable formats: Effortlessly change format of serialized data: binary, JSON, invent your own! https://github.com/scala/pickling
and inlined at the use-site. Flexible: Using typeclass pattern, retroactively make types serializable NO BOILERPLATE: Typeclass instances generated at compile-time pluggable formats: Effortlessly change format of serialized data: binary, JSON, invent your own! typesafe: Picklers are type-specialized. Catch errors at compile-time! https://github.com/scala/pickling
https://github.com/scala/pickling scala> import json._ import json._ scala> case class Person(name: String, age: Int) defined class Person scala> Person("John Oliver", 36) res0: Person = Person(John Oliver,36)
customizable Before we can show these things,let's have a look at the building block of the framework... Generated picklers Standard pickle format Custom picklers for specific types Custom pickle format
position def pickle(arr: Array[Byte], i: Int, x: T): Int // returns result plus next read position def unpickle(arr: Array[Byte], i: Int): (T, Int) } Elegant programming pearl that comes from functional programming. A composable and "constructive" way to think about persisting data. Compose picklers for simple types to build picklers for more complicated types What is a pickler? simplified version of what’s actually used in scala- pickling https://github.com/scala/pickling
some basic types like primitives 1 Picklers for base types Functions that combine existing picklers to build compound picklers 2 example: combinator that takes a Pickler[T] and returns a Pickler[List[T]]
an Int pickler and a String pickler val myPairPickler = tuple2Pickler(intPickler, stringPickler) What’s the type? Can we combine them automatically? Pickler[T], can pickle objects of type T def pickle(implicit pickler: Pickler[(Int, String)]) = { pickler.pickle((32, “yay!”)) } Goal: Can take intPickler and stringPickler as implicit parameters tuple2Pickler can be an implicit def https://github.com/scala/pickling
talk to a clojure app toy builder implementation: scala> import scala.pickling._ import scala.pickling._ scala> import edn._ import edn._ scala> case class Person(name: String, kidsAges: Array[Int]) defined class Person scala> val joe = Person("Joe", Array(3, 4, 13)) joe: Person = Person(Joe,[I@3d925789) scala> joe.pickle.value res0: String = #pickling/Person { :name "Joe" :kidsAges [3, 4, 13] }
type Pickler[Foo] in scope, you can pickle instances of it types for which an implicit pickler is in scope types for which our framework can generate picklers classes case classes generic classes singleton objects primitives & primitive arrays ... can’t (yet): instances of inner classes, Types https://github.com/scala/pickling
type Pickler[Foo] in scope, you can pickle instances of it types for which an implicit pickler is in scope types for which our framework can generate picklers classes case classes generic classes singleton objects primitives & primitive arrays ... IMPORTANT: The implicit picklers are used in the generation! can’t (yet): instances of inner classes, Types https://github.com/scala/pickling
2.10.2 No support for inner classes, yet ScalaCheck tests Very soon: support for cyclic object graphs (for release 0.9.0) https://github.com/scala/pickling
the next few months SIP for Scala 2.11 Integration with sbt, Spark, and Akka, ... Experiment: use Scala-pickling to speed up Scala compiler Release 0.8.0 for Scala 2.10.2 No support for inner classes, yet ScalaCheck tests Very soon: support for cyclic object graphs (for release 0.9.0) https://github.com/scala/pickling
future { val result = transform(data) sender ! Response(result) } } Potential hazards when using closures incorrectly: • Memory leaks • Race conditions, due to capturing mutable references • Runtime serialization errors, due to unintended capture of references akka actor spawns a future to concurrently process incoming reqs not a stable value! http://docs.scala-lang.org/sips/pending/spores.html
helper = Helper("the helper") val fun: Int => Unit = (x: Int) => { val result = x + " " + helper.toString println("The result is: " + result) } } Serialization of fun throws a NotSerializableException. Why? doesn’t extend serializable http://docs.scala-lang.org/sips/pending/spores.html
(x: Int) => { val result = x + " " + h.toString println("The result is: " + result) } } an alternative way to create closure-like objects, in a way where the environment is controlled
(x: Int) => { val result = x + " " + h.toString println("The result is: " + result) } } an alternative way to create closure-like objects, in a way where the environment is controlled The body of a spore consists of two parts: 1. a sequence of local value (val) declarations only, and 2.a closure.
(x: Int) => { val result = x + " " + h.toString println("The result is: " + result) } } an alternative way to create closure-like objects, in a way where the environment is controlled The body of a spore consists of two parts: 1. a sequence of local value (val) declarations only, and 2.a closure. The closure of a spore has to satisfy the following rule. All free variables of the closure body have to be either 1. parameters of the closure, or 2.declared in the preceding sequence of local value declarations.
APIs safer by expecting a Spore instead of a function By requiring spores in your public APIs you can prevent users from introducing hazards, like race conditions. Make your users more happy by preventing them from shooting themselves in the foot! do you have state & asynchrony? http://docs.scala-lang.org/sips/pending/spores.html
discussion! Pull request for Scala 2.11 and Akka 2.2.1 in preparation Integration with Scala-pickling planned http://docs.scala-lang.org/sips/pending/spores.html
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