Imperative configs are out; Declarative configs are in
1–10 of 94 posts
Re: Imperative configs are out; Declarative configs are in
#2A good overview of why legacy CD systems cause so much pain in cloud-native environments
Re: Imperative configs are out; Declarative configs are in
#3This is an old debate surely? My first awareness of it was probably related to Django's settings.py back around 2007 but I got the feeling from discussions then that it was a discussion that had been bouncing around for a long time before that.
The counter-argument is that declarative configs inevevitably sprout programming-like features - and if they don't someone will write code to generate them.
(disclaimer - in true HN fashion I haven't properly RTFA'd - dinner is nearly ready and I'm feeling bold)
Re: Imperative configs are out; Declarative configs are in
#4I.... don't buy the initial example. Google maps is still an imperative list of directions. It just keeps track of the current pointer for you, and is able to reroute. If anything, that is an example that a dynamic action plan is more adaptable than a static one.
That said, declarative clearly has advantages when it can work. You probably still want a "break glass" way to see what the actual steps that will be taken are, but can get surprisingly far without that.
Re: Imperative configs are out; Declarative configs are in
#5This is an old debate surely? My first awareness of it was probably related to Django's settings.py back around 2007 but I got the feeling from discussions then that it was a discussion that had been bouncing around for a long time before that. The counter-argument is that declarative configs inevevitably sprout programming-like features - and if they don't someone will write code to generate them. (disclaimer - in t…
Yep the idea of declarative winning out over imperative is nothing new. Yet for some reason, most deployment systems make you go through an imperative flow if you want to orchestrate releases.
Re: Imperative configs are out; Declarative configs are in
#6I.... don't buy the initial example. Google maps is still an imperative list of directions. It just keeps track of the current pointer for you, and is able to reroute. If anything, that is an example that a dynamic action plan is more adaptable than a static one. That said, declarative clearly has advantages when it can work. You probably still want a "break glass" way to see what the actual steps that will be taken…
Oh totally that declarative can and will often compile down to imperative. The question is what do you ask the user for? My take is Google maps is declarative in the sense that you ask for your destination, your constraints (e.g. no highway), and time to leave, and it dynamically generates the underlying imperative steps like you said (but continuously adapt if you go off course, which you cannot do unless the initial input was declarative).
Re: Imperative configs are out; Declarative configs are in
#7[deleted]
Re: Imperative configs are out; Declarative configs are in
#8I.... don't buy the initial example. Google maps is still an imperative list of directions. It just keeps track of the current pointer for you, and is able to reroute. If anything, that is an example that a dynamic action plan is more adaptable than a static one. That said, declarative clearly has advantages when it can work. You probably still want a "break glass" way to see what the actual steps that will be taken…
Oh totally that declarative can and will often compile down to imperative. The question is what do you ask the user for? My take is Google maps is declarative in the sense that you ask for your destination, your constraints (e.g. no highway), and time to leave, and it dynamically generates the underlying imperative steps like you said (but continuously adapt if you go off course, which you cannot do unless the initia…
That example still feels off. The "offline printout" was done in a very declarative way. It is just fixed on the execution plan. (And, quite frankly, less obnoxious to me if I decide to stop and get gas or food.)
You can even prepare alternative routes ahead of time, if you want to speculate on conditions. Is a good idea to role play some of that ahead of the time, in any case.
Re: Imperative configs are out; Declarative configs are in
#9"My dad switched from working with a map printout without knowing real-time conditions, the imperative flow, to Google Maps with turn-by-turn directions, the declarative flow."
There is no such thing as an imperative or declarative "flow". By its very definition, declarative does not have "flow". It is just a statement. Imperative (in programming) literally means "describing steps that change state". Declarative (in programming) literally means "describing a state which is desired".
Declarative would be "I want a cheeseburger." Imperative would be "Get me a bun, and some lettuce, and tomato, and mayo, and raw meat. Cook the meat on a grill at high heat, flipping half way. Put the mayo on the bottom of the bun, then the meat, then the lettuce, then the tomato, then put on the top of the bun. Give it to me."
It's still strange to me how people learn about "magic words" like declarative and imperative, and then try to ssstttrrreeeeettttttcccccccchhhhhhhhhhh their meaning into some new paradigm that they have just thought up.
There is no such thing as an imperative configuration file. A configuration file describes how a program should be configured. Even when the configuration file "describes a series of steps to change state", it's still declarative, because the configuration file is still declaring to the program how to operate. It's the program that is imperative or declarative, depending on how it interprets and acts on the configuration file. (This is made clearer in programs like Ansible, which, within the exact same configuration file, supports both declarative and imperative statements)
Before you say "what about template files! jinja2! go templates! hcl!", that is merely a DSL, which is no longer a configuration file; it is effectively a program in a crude programming language, interpreted by an interpreter (the program loading the file).
(edit: I agree with the author's point! But I suggest we stop using these terms 'declarative' and 'imperative', and instead say "let's write programs that are functional enough that we don't need to write configuration files that are mini-programs")
Re: Imperative configs are out; Declarative configs are in
#10Earlier quoted context omitted.
Oh totally that declarative can and will often compile down to imperative. The question is what do you ask the user for? My take is Google maps is declarative in the sense that you ask for your destination, your constraints (e.g. no highway), and time to leave, and it dynamically generates the underlying imperative steps like you said (but continuously adapt if you go off course, which you cannot do unless the initia…
That example still feels off. The "offline printout" was done in a very declarative way. It is just fixed on the execution plan. (And, quite frankly, less obnoxious to me if I decide to stop and get gas or food.) You can even prepare alternative routes ahead of time, if you want to speculate on conditions. Is a good idea to role play some of that ahead of the time, in any case.
That makes sense. I'm not necessarily arguing for continuous intelligence in this post, just that declarative configs enable it. Even the initial conversion of a destination to a set of directions is a compilation of declarative to imperative. Imagine if Google Maps was truly imperative and asks you to input the individual roads you want ahead of time - then it would not be useful.