Archaeology: Raw import from the Tezos project

v0.1: Initial release

v0.2:

• complete rewrite: the library pivots towards caches

v0.3:

• Rename Loose as Weak
• Rename CACHE as CACHE_MAP (and associated name changes) to hint at key-value storage
• introduce set-caches (CACHE_SET) which are simple value caches (not key-value caches)
• introduce clear to empty caches entirely
• fix singleton-collection bug
• simplify code in main entry module

v0.4:

• Handle reinsertion as promotion
• bugfix: do not hard-fail when removing the single element of a collection
• Wrappers for Lwt, Lwt-Option, and Lwt-Result
• rename Strict to Strong (as opposed to Weak)

v0.5:

• Fix leakiness of Lwt-wrapped caches (clean-up functions would hold onto bindings)
• Fix race condition in Lwt-wrapped caches (rejection of a non-held promise cannot cause removal of a held promise)
• Folding in Lwt-wrapped caches ignores failed promises (aligns semantics with automatic cleaning)
• Improve documentation of Lwt-wrapped caches

v0.6:

• Add specialised 0-sized and 1-sized caches
• Improved test coverage
• Improved documentation

v0.7:

• Add filter to caches
• Support for empty and singleton caches in ringo-lwt