Language interoperability

Language interoperability is the capability of two different programming languages to natively interact as part of the same system and operate on the same kind of data structures. There are many ways programming languages are interoperable with one another. HTML, CSS, and JavaScript are interoperable as they are used in tandem in webpages. Some object oriented languages are interoperable thanks to their shared hosting virtual machine (e.g. .NET CLI compliant languages in the Common Language Runtime and JVM compliant languages in the Java Virtual Machine). Object models are standardised models which allow objects to be represented in a language-agnostic way, such that the same objects may be used across programs and across languages. CORBA and the COM are the most popular object models. A virtual machine (VM) is a specialised intermediate language that several different languages compile down to. Languages that use the same virtual machine can interoperate, as they will share a memory model and compiler and thus libraries from one language can be re-used for others on the same VM. VMs can incorporate type systems to ensure the correctness of participating languages and give languages a common ground for their type information. The use of an intermediate language during compilation or interpretation can provide more opportunities for optimisation. Foreign function interfaces (FFI) allow programs written in one language to call functions written in another language. There are often considerations that preclude simply treating foreign functions as functions written in the host language, such as differences in types and execution model. Foreign function interfaces enable building wrapper libraries that provide functionality from a library from another language in the host language, often in a style that is more idiomatic for the language. Most languages have FFIs to C, which is the "lingua franca" of programming today. Object oriented languages attempt to pair containers of data with code, but how each language chooses how to do that may be slightly different.