It seems like the choice of a stacklike Arena API makes the examples a little more confusing than needed. An arena doesn't necessarily mean allocation 2 must be

It seems like the choice of a stacklike Arena API makes the examples a little more confusing than needed. An arena doesn't necessarily mean allocation 2 must be freed before allocation 1. If this seems cool to you, check out Zig. The libraries use a similar convention where code that might allocate requires passing an allocator, which may be an arena, or something cool we don't even know about yet.