Immutable datastore library?

I would like to use Postgres as an immutable data store. A subject table would have a timestamp column, and that would
beadded to what would otherwise be the primary key. 

Trap updates and turn them into inserts. Have an associated _deleted table. Trap deletes and turn them into inserts of
theprimary key into that table. 

Create a view that only shows the non-deleted records with the most recent timestamps.

Stored procedure to do all that to a table. Event trigger to drop and re-create the view on changes to the table
columns.

I think that's about it. Seems an obvious and nice general-purpose thing to do. It also seems like something someone
mighthave already done, but googling "immutable postgres" pulls up things about writing functions. 

Does anyone know of a project that has already done this?