[seiflotfy]

This is awesome... question though: ```pub fn HyperLogLog(comptime p: u8) type { return struct { dense: [1<<p]u6;

            const Self = @This();
            pub fn init() Self {
                var s = Self{};
                for (s.dense) |*x| x.* = 0;
                return s;
            }
        }
    }```

doesn't this allocate 1<<p upfront though. If yes then the HLL of size 16384 bytes upfront which kinda beats the purpose of having a sparse representation no?

[kristoff_it]

> doesn't this allocate 1<<p upfront though

Yes, it does. The idea (see the last code snipped in that post), is that the user delays the creation of the HLL until they are ready to switch to a dense representation. Before then, they just use a std.AutoHashMap directly.

Or, alternatively, the HLL could use the same buffer for both dense and sparse representation (see the Redis code).