I'm happy to report that the Vlerq project is on track. The current "v7" code now has the same operators as Ratcl's "v4" had, including grouping / ungrouping and joins. It has more powerful "where" and "calc" operators than v4, due to Lua's closures. But at this stage, v7 is still way behind v4 in terms of stability, robustness, and test suite coverage. And lots of memory leaks.

I'm very pleased with v7 because it includes (early) code for supporting missing values and mutable/translucent view layers. This is where the v4 design had reached its limits. And the whole code base is only around 5K lines of C plus 200 lines of Lua. Several design choices, particularly the main internal data structures, have stood the test of time and have survived virtually as is in all the last rewrites. With a fair amount of functionality implemented, this indicates that the core design is sound (even if some code is still pretty ugly).

Onwards!