The type of a path. paths are strings. They are used to determine the location where the data should be persisted on disk.

Keys in Map-like storage functors are represented as strings.

BACKEND is the module type defining the backend for persisting data to disk. It is used by the functors in Store_utils to create Storage modules that persist data structures on disk.

Module type respresenting a Mutable_value that is persisted on store.

This module contains information about where to store and retrieve contents of storage persisted on disk.

KEY is a module type used to construct Map-like storage modules. It defines how keys are used to determine a path on disk.

VALUE is a module type to define values that will be persisted on disk via storage modules.

Generic module type for maps to be persisted on disk.

Generic module type for append-only maps to be persisted on disk.

Nested_map is a map where values are indexed by both a primary and secondary key. It allows more flexibility over a map whose keys are tupls of the form `(primary_key, secondary_key)`. In particular, it provides functions to retrieve all the bindings in a map that share the same primary_key.

COMPARABLE_KEY is a module type used to define secondary keys in nested maps.