Finished April 2021 recap post

docs/_posts/2021-04-30-luau-recap-april-2021.md

@@ -3,18 +3,57 @@ layout: single
 title:  "Luau Recap: April 2021"
 ---
 
-Luau is our new language that you can read more about at [https://roblox.github.io/luau](https://roblox.github.io/luau).
+Luau is our new language that you can read more about at [https://roblox.github.io/luau](https://roblox.github.io/luau). Another busy month in Luau with many performance and typechecking improvements.
 
-[Cross-posted to the [Roblox Developer Forum](TBD).]
+[Cross-posted to the [Roblox Developer Forum](https://devforum.roblox.com/t/luau-recap-april-2021/).]
 
 ## Features
 
+Luau implementation now provides an API for type-aware autocomplete suggestions.
+
+Roblox Studio will be the first user of this API and we plan for a new beta feature to come soon in addition to existing Luau-powered beta features like Go To Declaration, Type Hovers and Script Function Filter (you should check those out!)
+
 ## Typechecking improvements
 
+We've made various improvements to the Luau typechecker:
+
+* Fixed an issue with `table.insert` function signature
+* Made improvements to cyclic module import detection and error reporting
+* Added new linter pass that will report uses of deprecated Roblox APIs
+* Fixed `assert` function declaration to accept a second optional string argument
+* Fixed incorrect error on modification of table intersection type fields
+* When using an 'or' between a nillable type and a value, the resulting type is now inferred to be non-nil
+
+We have also made improvements to type output in error messages and made additional improvements to parser recovery from errors.
+
+As usual, typechecking improvements will not break execution of your games even if new errors get reported.
+
 ## Performance improvements
 
+Performance is a very important part of Luau implementation and we continue bringing in new performance optimizations:
+
+* We've finished the work on internal `vector` value type that will be used by `Vector3` type in Roblox. Improvements of up to 10x can be seen for primitive operations and some of our heavy `Vector3` benchmarks have seen 2-3x improvement. You can read more about this feature [on Roblox Developer forums](https://devforum.roblox.com/t/native-luau-vector3-beta/)
+* By optimizing the way string buffers are handled internally, we bring improvements to string operations including `string.lower`, `string.upper`, `string.reverse`, `string.rep`, `table.concat` and string concatenation operator `..`. Biggest improvements can be seen on large strings
+* Improved performance of `table.insert` and `table.remove`. Operations in the middle of large arrays can be multiple times faster with this change
+* Improved performance of internal table resize which brings additional 30% speedup for `table.insert`
+* Improved performance of checks for missing table fields
+* Improved performance of table lookup with an index operator and a string: `t["name"]`
+
+## Generic functions
+
+We had to temporarily disable generic function definitions last month after finding critical issues in the implementation.
+
+While they are still not available, we are making steady progress on fixing those issues and making additional typechecking improvements to bring them back in.
+
 ## Debugger improvements
 
-## Library changes
+Debugging is now supported for parallel Luau Actors in Roblox Studio.
 
-## Coming soon...
+Read more about the feature [on Roblox Developer forums](https://devforum.roblox.com/t/parallel-lua-beta/) and try it out yourself.
+
+## Behavior changes
+
+Backwards compatibility is very important for Luau, but sometimes a change is required to improve the language or performance. Even still, we try to keep impact of these changes to a minimum:
+
+* __eq tag method will always get called for table comparisons even when a table is compared to itself.
+* assert function will return only the first argument as the result.