3 ms·

That is so wonderfully fascinating to me. You could just download a file into a variable and when that variable goes out of scope/has no more references it’d ju

That is so wonderfully fascinating to me. You could just download a file into a variable and when that variable goes out of scope/has no more references it’d just be automatically “deleted”. Since there’s no longer a concrete “thing” called a file, you can organize them however you want and with whatever “metadata” you want by having a dict with the metadata you want and some convention like :file as the key that points to the body. Arbitrary indexes too; any number of data structures could all share a reference to the same variable. Simple databases are just made up of collections of objects. Foreign key constraints? Just make the instance variable type a non-nullable type. Indexes? Lists of tuples that point to the objects. More complex databases and queries can provide a set of functions as an API. You can write queries in SQL or you can just provide a map/filter/reduce function with the predicate written in normal code. Graph databases too: you can just run Dijkstra’s algorithm or TSP or whatever directly on a rich persistent data structure. Thanks for the neat idea to riff on. I like it! Thinking about it in practice makes me a little anxious, but the theory is beautiful.

mcherm 3y ago
So, I've occasionally played around with a language that pretty nearly does this. Mumps is a language developed in 1967, and it is still in use in a few places including the company where I work. The language is old enough that the first version of it has "if" but no "else". When they added "else" later on it was via a hack worthy of this post: the "if" statement simply set a global variable and the new "else" statement checked that. As a result, "if-else" worked fine but only so long as you don't use another "if" nested within the first "if" clause (since that would clobber the global variable). That was "good enough" and now 50 years later you still can't nest "if" statements without breaking "else". But this very old language had one brilliant idea: persistence that works very much the way you describe. Any variable whose name begins with "^" is persisted -- it is like a global variable which is global, not just to this routine but to all of the times we execute the program. It is typical to create single variables that contain a large structure (eg: a huge list with an entry for each customer, indexed by their ID, where the entry contains all sorts of data about the customer); we call these "tables" because they work very much like DB tables but are vastly simpler to access. There's no "loading" or impedance mismatch... just refer to a variable. Interestingly, the actual implementation in modern day uses a database underneath, and we DO play with things like the commit policy on the database for performance optimization. So in practice the implementation isn't as simple as what you imply.
- govg 3y ago
  That global persistence model across executions is very fascinating. If you don't mind, could you explain what line of work this is and how it helps the use case? I have encountered similar concepts at my old job in a bank, where programs could save global variables in "containers" (predates docker IIRC) and then other programs could access this.
  - vdqtp3 3y ago
    https://www.oit.va.gov/Services/TRM/StandardPage.aspx?tid=6402 https://www.oit.va.gov/Services/TRM/StandardPage.aspx?tid=64...
  - mcherm 3y ago
    These days, Mumps is mostly used in elderly systems in the insurance and banking industries. In my case it is banking. I work at Capital One and one of the financial cores we use is Profile from FIS, which is (at least in older versions) built in Mumps.

mcherm 3y ago

So, I've occasionally played around with a language that pretty nearly does this. Mumps is a language developed in 1967, and it is still in use in a few places including the company where I work. The language is old enough that the first version of it has "if" but no "else". When they added "else" later on it was via a hack worthy of this post: the "if" statement simply set a global variable and the new "else" statement checked that. As a result, "if-else" worked fine but only so long as you don't use another "if" nested within the first "if" clause (since that would clobber the global variable). That was "good enough" and now 50 years later you still can't nest "if" statements without breaking "else". But this very old language had one brilliant idea: persistence that works very much the way you describe. Any variable whose name begins with "^" is persisted -- it is like a global variable which is global, not just to this routine but to all of the times we execute the program. It is typical to create single variables that contain a large structure (eg: a huge list with an entry for each customer, indexed by their ID, where the entry contains all sorts of data about the customer); we call these "tables" because they work very much like DB tables but are vastly simpler to access. There's no "loading" or impedance mismatch... just refer to a variable. Interestingly, the actual implementation in modern day uses a database underneath, and we DO play with things like the commit policy on the database for performance optimization. So in practice the implementation isn't as simple as what you imply.

govg 3y ago
That global persistence model across executions is very fascinating. If you don't mind, could you explain what line of work this is and how it helps the use case? I have encountered similar concepts at my old job in a bank, where programs could save global variables in "containers" (predates docker IIRC) and then other programs could access this.
- vdqtp3 3y ago
  https://www.oit.va.gov/Services/TRM/StandardPage.aspx?tid=6402 https://www.oit.va.gov/Services/TRM/StandardPage.aspx?tid=64...
- mcherm 3y ago
  These days, Mumps is mostly used in elderly systems in the insurance and banking industries. In my case it is banking. I work at Capital One and one of the financial cores we use is Profile from FIS, which is (at least in older versions) built in Mumps.