Store mutable data in RAM, and immutable data on Disk

[konard]

Figi is example of type. ArchivedFigi is an example of archived version of type.

S is state. S1 is first state. Sn is last state.

States S(1) … S(n - 1) can be used as an archive and can be stored on Disk. Last state S(n) can be stored in RAM.

X->Y are recorded atomic state transitions. These make up append only log file used as an archive.