Not so much interesting, but it rather looks grossly inefficient and a complete antipattern in terms of data layout, unless Erlang has a very, very capable allocator, that is able to correctly colocate all these linked structures. Still, the bizarre overhead multiplies bandwidth requirements, and pointer chasing multiplies memory access latency penalties.
It was going from a binary like <<"foobar">> to a linked list string to print out as part of the crash dump, so something like ['<', '<', 'f' ... etc which absolutely blew up the memory, considering that the original binary was pretty big.
The tagged pointer/value trick (using the fact that allocations are aligned to boundaries thus allowing for 2-3 bits of information you can use to tell which is which) is a trick we used in my first MacOS app 30 years ago, though we used bits at other end since you couldn't allocate the full address space on those old Macs.
