Glossary

Actors

Library authors identify the required functionality they want to parametrize over.

Provider authors implement these building blocks. There can be several different implementations of the same Traits, each with different characteristics (e.g., blocking/non-blocking, using/avoiding certain dependencies).

Clients (end users) write the final code that utilizes everything else. Clients decide which providers to use at runtime and instantiate the parametrized libraries with them.

Operations

Lookup: A parametrized library performs a lookup at runtime in the provider structure supplied to it to find the implementation of the required Trait.

Implement: A provider provides an implementation for a given set of Traits.

Instantiate: A client chooses which provider to supply to their parametrized libraries to use them.

Actor	Operation
Library authors	Lookup
Provider authors	Implement
Clients	Instantiate

Terminology

Trait: A module signature grouping some functionality.

Implementation: A module that implements a Trait signature.

Parametrized Library: A library that requires the functionality contained in one or several Traits. It can compile without having access to actual Trait implementations.

Binding: The pair of a Trait and an actual implementation for it.

Provider: A list of bindings.

Packed Provider: A provider coupled with its required internal state (an OCaml value that behaves like an object, but isn't one).