Freezer

Freezer is inspired by / ripped off from Rich Hickey's talk, The Database as a Value and Datomic.

Freezer is an immutable value store. All changes to the store create a new database, as opposed to changing the database in place. Once you have pulled a database out of the store, it never changes. It is a fixed view of the store at that point in time.

Freezer is made up of a few basic components:

• FRZStore is the top-level thing. The store is where you go to get the current database or get a transactor to perform changes.
• FRZDatabase is how you get data out of the store. It is immutable. It never changes in place.
• FRZTransactor is responsible for adding or removing values from the store.

IDs

IDs are used to group key-value pairs into a single entity. They can be any arbitrary string.

Keys

Freezer does not store objects. Instead, it stores an arbitrary collection of key-value pairs, grouped by an ID.

A collection of keys, grouped by ID, may be transformed into, for example, a Mantle model object. But note that model object is simply a view on the data. It is not the thing itself.

Changes

Stores provide a RACSignal of changes which are applied to the store. This signal can be filtered, throttled, etc. as needed to find out about the changes your app cares about.

Thread-safety

Freezer is completely thread-safe. Databases may be read from in any thread and FRZTransactor may add or remove values in any thread.

If the database is immutable... does that mean the store grows without bound?

Yuuuuuuuuuup. But you can call -[FRZTransactor trim:] to trim the store down to the latest database.

Should I use this?

Nooooooooope. Or at least not yet. Freezer's still in a constant state of flux.