4 ms·

‘Prelude’ is the set of standard functions and types that you don't have to import to use. Python comes with a rich standard library, but most require imports t

‘Prelude’ is the set of standard functions and types that you don't have to import to use. Python comes with a rich standard library, but most require imports to use. > How many characters do you have to change if you want it purely in memory? When the question is if ‘K can reduce line count by a factor 1000’, shorter keywords hardly cut it. ‘setdefault’ is wordier than ‘?’, but as something you're only going to use on occasion, so what? And d.setdefault(_, len(d)) is something you'll use maybe once a year. shelve acts like a dict, so you can do the setdefault dance the same way on in-memory dicts.

geocar 7y ago
> ‘Prelude’ is the set of standard functions and types that you don't have to import to use. Python comes with a rich standard library, but most require imports to use. I might not understand this about python. $ python3 Python 3.7.6 (default, Dec 30 2019, 19:38:26) [Clang 11.0.0 (clang-1100.0.33.16)] on darwin Type "help", "copyright", "credits" or "license" for more information. >>> Counter Traceback (most recent call last): File "<stdin>", line 1, in <module> NameError: name 'Counter' is not defined Should that have worked? Is there something wrong with my Python installation? > but as something you're only going to use on occasion, so what? And d.setdefault(_, len(d)) is something you'll use maybe once a year. If it takes that many keystrokes, you're definitely only going to use it once per year! This is the normal way you make enumerations in q/k. The low number of source-code bytes is the major feature in k. I've written some on why this is valuable, but at the end of the day, I don't really have anything more compelling than try it you might like it, and it works for me. This is something I'm working on though. - https://news.ycombinator.com/item?id=8476113 https://news.ycombinator.com/item?id=8476113 - https://news.ycombinator.com/item?id=10876975 https://news.ycombinator.com/item?id=10876975
- Veedrac 7y ago
  Counter is not in Python's prelude. Therefore you have to import it in order to use it. My comment about prelude was in response to you saying I was using Python's “language+plus-its-entire-ecosystem”. This is not true; Counter is part of the standard library that comes with the language. It is not from a third-party package. > If it takes that many keystrokes, you're definitely only going to use it once per year! This is the normal way you make enumerations in q/k. You don't use this frequently in other languages because you almost never care about the index of a value in a hash table (because it's ridiculous), and you almost never want to brute-force unique a list (because it's a footgun).
  - geocar 7y ago
    > you saying I was using Python's “language+plus-its-entire-ecosystem”. This is not true; Counter is part of the standard library that comes with the language. It is not from a third-party package. I'm not sure I agree "third-party package" is a good/useful place to draw the line, but I don't think it's terribly important. Sorry. > you almost never care about the index of a value in a hash table (because it's ridiculous) So I want to query all of the referrer urls I've seen recently. I only see a few of them, so I want to have a table of all the URLs, and another table with one row per event (landing on my page). In SQL, you might have a foreign-key operation, but in q, I can also make the enumeration directly. I don't really care about the value of the index, just that I have one.
    - Veedrac 7y ago
      I wouldn't want to use an index as a long-lived key like that, since it makes ops like deletion a footgun. For temporary calculations I'd just `{u: Url(u) for u in url_strings}` for the table of URLs, and stick the `Url` objects in the table of events.
      - geocar 7y ago
        I don’t understand any of this. I don’t know what footgun is. I have no idea what a “URL” object is or how you stick it in a table of events (on disk? in memory? in a remote process called a “database”). I’m don’t know what you mean by temporary calculations. I have fifty billion of these events to handle every day, and I do this on one server (that is actually doing other things as well). It is not an option to “just” do anything at this scale if I want to keep costs under control.
        Veedrac 7y ago
        Sorry, it's a bit weird not sharing a lexicon. I get the impression Q is a whole different genealogy of programmers. In Python, although you can just use shelve to store data on disk, in practice this is considered a bad idea beyond very simple cases. Valuable data wants the guarantees that real databases provide, like ACID. shelve doesn't provide this, and IIUC nor does kdb+. So if you're handling 50 billion events a day, live, and you need these to persist, you'd use SQL or something similar. That would then ultimately determine how you add and manipulate records. If you don't care that much if you lose the data on a crash, that's when we're talking about temporary calculations. In Python, rather than having two tables like (eg.) URLs: url_id url count 1 google.com 300 2 python.org 400 3 example.net 200 Requests: request_id data url_id 1 'spam' 2 2 'eggs' 2 ... 900 'ham' 1 you would make a custom type, aka. ‘Url’, containing ‘url’ and ‘count’ as object fields, and then store your requests as a list containing references to those ’Url’s. urls = { "google.com": Url("google.com", 300), "python.org": Url("python.org", 400), "example.net": Url("example.net", 200), } requests = [ Request("spam", urls["python.org"]), Request("eggs", urls["python.org"]), ..., Request("ham", urls["google.com"]), ]

geocar 7y ago

> ‘Prelude’ is the set of standard functions and types that you don't have to import to use. Python comes with a rich standard library, but most require imports to use. I might not understand this about python. $ python3 Python 3.7.6 (default, Dec 30 2019, 19:38:26) [Clang 11.0.0 (clang-1100.0.33.16)] on darwin Type "help", "copyright", "credits" or "license" for more information. >>> Counter Traceback (most recent call last): File "<stdin>", line 1, in <module> NameError: name 'Counter' is not defined Should that have worked? Is there something wrong with my Python installation? > but as something you're only going to use on occasion, so what? And d.setdefault(_, len(d)) is something you'll use maybe once a year. If it takes that many keystrokes, you're definitely only going to use it once per year! This is the normal way you make enumerations in q/k. The low number of source-code bytes is the major feature in k. I've written some on why this is valuable, but at the end of the day, I don't really have anything more compelling than try it you might like it, and it works for me. This is something I'm working on though. - https://news.ycombinator.com/item?id=8476113 https://news.ycombinator.com/item?id=8476113 - https://news.ycombinator.com/item?id=10876975 https://news.ycombinator.com/item?id=10876975

Veedrac 7y ago
Counter is not in Python's prelude. Therefore you have to import it in order to use it. My comment about prelude was in response to you saying I was using Python's “language+plus-its-entire-ecosystem”. This is not true; Counter is part of the standard library that comes with the language. It is not from a third-party package. > If it takes that many keystrokes, you're definitely only going to use it once per year! This is the normal way you make enumerations in q/k. You don't use this frequently in other languages because you almost never care about the index of a value in a hash table (because it's ridiculous), and you almost never want to brute-force unique a list (because it's a footgun).
- geocar 7y ago
  > you saying I was using Python's “language+plus-its-entire-ecosystem”. This is not true; Counter is part of the standard library that comes with the language. It is not from a third-party package. I'm not sure I agree "third-party package" is a good/useful place to draw the line, but I don't think it's terribly important. Sorry. > you almost never care about the index of a value in a hash table (because it's ridiculous) So I want to query all of the referrer urls I've seen recently. I only see a few of them, so I want to have a table of all the URLs, and another table with one row per event (landing on my page). In SQL, you might have a foreign-key operation, but in q, I can also make the enumeration directly. I don't really care about the value of the index, just that I have one.
  - Veedrac 7y ago
    I wouldn't want to use an index as a long-lived key like that, since it makes ops like deletion a footgun. For temporary calculations I'd just `{u: Url(u) for u in url_strings}` for the table of URLs, and stick the `Url` objects in the table of events.
    - geocar 7y ago
      I don’t understand any of this. I don’t know what footgun is. I have no idea what a “URL” object is or how you stick it in a table of events (on disk? in memory? in a remote process called a “database”). I’m don’t know what you mean by temporary calculations. I have fifty billion of these events to handle every day, and I do this on one server (that is actually doing other things as well). It is not an option to “just” do anything at this scale if I want to keep costs under control.
      - Veedrac 7y ago
        Sorry, it's a bit weird not sharing a lexicon. I get the impression Q is a whole different genealogy of programmers. In Python, although you can just use shelve to store data on disk, in practice this is considered a bad idea beyond very simple cases. Valuable data wants the guarantees that real databases provide, like ACID. shelve doesn't provide this, and IIUC nor does kdb+. So if you're handling 50 billion events a day, live, and you need these to persist, you'd use SQL or something similar. That would then ultimately determine how you add and manipulate records. If you don't care that much if you lose the data on a crash, that's when we're talking about temporary calculations. In Python, rather than having two tables like (eg.) URLs: url_id url count 1 google.com 300 2 python.org 400 3 example.net 200 Requests: request_id data url_id 1 'spam' 2 2 'eggs' 2 ... 900 'ham' 1 you would make a custom type, aka. ‘Url’, containing ‘url’ and ‘count’ as object fields, and then store your requests as a list containing references to those ’Url’s. urls = { "google.com": Url("google.com", 300), "python.org": Url("python.org", 400), "example.net": Url("example.net", 200), } requests = [ Request("spam", urls["python.org"]), Request("eggs", urls["python.org"]), ..., Request("ham", urls["google.com"]), ]