Update readme

README.md

@@ -2,19 +2,27 @@ loot-condition-interpreter
 ==========================
 
 An experimental library for parsing and evaluating LOOT's metadata condition
-strings. Written in Rust. Very incomplete.
+strings. This library improves upon LOOT's existing implementation in the
+following ways:
 
-Goals:
+- Condition expressions are parsed into an intermediate representation instead
+  of being stringly typed, which allows parsing and evaluation to be separated.
+- State is uncoupled by necessity, and Rusts's concurrency guarantees mean it
+  can be accessed more efficiently.
+- Results are cached with more granularity, per function instead of per
+  expression, improving performance when expressions are not entirely different.
+- Result caching is guided by benchmarks, so results aren't cached
+  unnecessarily.
+- Reading executable versions doesn't involve calling out to the shell and
+  piping several commands together when on Linux.
 
-- [x] Explore parsing conditions into an intermediate representation, then
-  evaluating from that representation. LOOT's current parser evaluates
-  conditions while parsing them, tightly coupling the two operations.
-- [ ] Explore more granular result caching. LOOT's current caching maps each
-  condition string to its result, which can't re-use results in compound
-  conditions.
-- [x] Explore round trip serialisation from the intermediate representation.
-- [ ] Evaluate the cost/benefit of integrating into LOOT, replacing the existing
-  code.
+The code is also not as much of a mess, it's got benchmarks, and probably better
+test coverage.
+
+The library is still experimental because it currently lacks:
+
+- an FFI for LOOT to call it through.
+- good error handling, details about parsing errors are not exposed.
 
 The tests need the [testing-plugins](https://github.com/WrinklyNinja/testing-plugins)
 and the [LOOT API v0.13.8](https://github.com/loot/loot-api/releases/tag/0.13.8)