Polyglot language interoperation

Java Specialists Symposium 2011

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Making Java Fun Again

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Performance Anti-Patterns
Convenor: Ben Evans
Participants: Ben Evans Sven Reimers Michael Hunger Elisabeth Kasimir Alexander Kasimir Kon Soulianidis Mike Nielson John Kostaras Marc Hoffmann Andriy Phil
Summary: Fact: Interopability is hard Why? Source is compiled to class (bytecode) clojure one class per method fn: -> fn$1134 What is hard? Everything is an object String(s) -> Ruby Strings are mutable Primitive Types Method Dispatch Semantics Scopes + Scoping Lambdas + Closures Multi-Return Annotations, (Generics,) Metadata Pass by reference / pass by value Inheritance Semantics Just looking at method dispatch Java Dispatch... Static Special Interface Virtual Virtual Method Call: 1. Mark 2. Pointer to class having list of pointers to methods (v-table), get the offset walk the inheritance Other language: $obj->$method(); Starting with reflection you end up with not typesafe method description. Java 7 introduces a type safe way: MethodType.methodType(retType, paramTypes) MethodHandles: Lookup -findVirtual(MethodType...) -getStatic -... results in MethodHandle mh mh.invoke(...); => unreflection is possible... Using MethodHandles can improve the performance: MH1->MH2->MH3 V1 -> V2 -> V3 -> (makes inling by hotspot possible) Covariant and Contravariant Disptach -> List<Pet> lp; List<Cats> lc; : is lc a lp ??? Inheritance: Ruby: Everything is an IRubyObject (The IRubyObject Approach) myObj = (IRubyObject) registry.get(...) Scala: has Any and AnyRef, no common super type to cast to What you really need: Registry foreign objects method linkages Type Biconversion Biconversion: java.lang.interop Primitives Strings Function types (i.e. lambda) Project DYNALINK (Attila Szegedi)
Recommendations: (as above)
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