hostlanguage

Hostlanguage, in computing, refers to the language in which a program, tool, or runtime is written or executes, and from which a guest or embedded language is invoked. The host provides the execution environment, memory management facilities, libraries, and the interfaces used by the guest language or components. This concept is widely used in programming language embedding, extension, and in compiler or toolchain design.

In embedding and extension scenarios, the host language runs the overall application while the guest language is used for adding extensibility or specialized behavior. The guest code is executed within the host’s runtime and can call into host services through defined interfaces or foreign-function interfaces. Examples commonly cited include embedding Lua or Python as scripting languages inside applications written in C or C++, and using domain-specific languages embedded within host programs via libraries or preprocessors. In such setups, performance and interoperability depend on the efficiency of the host–guest interface and the correctness of data conversion between the two languages.

In compiler and toolchain contexts, the host language is the language in which the compiler or tool itself is implemented, not the language it compiles. For instance, many historic and current compilers and tooling are written in C or C++, making those languages the host in development terms. The distinction helps separate the implementation language from the target or source languages being processed.

Key considerations when working with a host language include cross-language interoperability, ABI and type-system compatibility, memory management boundaries, and potential overhead from language boundaries. Well-designed FFI, clear ownership rules, and stable interfaces mitigate common integration challenges.