There are about six major conceptualizations of memory, which I’m calling “memory models”², that dominate today’s programming. Three of them derive from the three most historically important programming languages of the 1950s — COBOL, LISP, and FORTRAN — and the other three derive from the three historically important data storage systems: magnetic tape, Unix-style hierarchical filesystems, and relational databases.
These models shape what our programming languages can or cannot do at a much deeper layer than mere syntax or even type systems. Mysteriously, I’ve never seen a good explanation of them — you pretty much just have to absorb them by osmosis instead of having them explained to you — and so I’m going to try now. Then I’m going to explain some possible alternatives to the mainstream options and why they might be interesting.
Every modern programming environment handles all six of these memory models to some extent, which is one reason our systems are so complicated and hard to understand.