Functional purity is mostly unrelated to comprehensibility - comprehensible programs can be pure, or not, and the same goes for incomprehensible probgrams. The relevant background knowledge is some experience with programs.
If someone knows what both functional purity and abstraction are, they don't need to be told that they're different and one can have either one without the other.
"the abstraction of programming" is on the edge of bather and the part that isn't blather has nothing to do with impure programming.
And, if you don't understand that abstractions leak and that the real world (and machines) are stateful/not functional, you're in for it.
Pure functions are easier to think about than impure functions. It is easier to think about simpler things. Pure functions are simpler than impure functions because their result depends only on their parameters(complexity being correlated with the number of things on which a thing depends).
If purely functional programs in some language to accomplish some goal are harder to understand than stateful implementions, the appropriate response is not to criticize functional programming, but instead to try to find ways to make that language more understandable or more suitable for accomplishing that goal.
"And, if you don't understand that abstractions leak and that the real world (and machines) are stateful/not functional, you're in for it."
I think there are actually conceptual advantages to thinking of the universe functionally(as a tail-recursive function with all the "state" contained in the parameters), in case a method for time travel is ever developed. It seems as though it would be easier to reason about than it would be if the universe is treated as stateful.
> Pure functions are easier to think about than impure functions.
Many pure functions are easier to think about than their impure equivalents, but it's certaintly not the case the all pure functions are easier to think about than their impure equivalents.
> Pure functions are simpler than impure functions because their result depends only on their parameters.
And, because pure functions have no state, many pure functions have to drag along state through their parameters that they don't need/use but that their callees need/use.
> (complexity being correlated with the number of things on which a thing depends).
The complexity of the things matters a lot as well.
> If purely functional programs in some language to accomplish some goal are harder to understand than stateful implementions, the appropriate response is not to criticize functional programming, but instead to try to find ways to make that language more understandable or more suitable for accomplishing that goal.
"the appropriate response"? Sorry, I have work to do, work that doesn't include making advocates of functional programming happy, let alone spending time on things that they haven't been able to do. (Some of the developers of functional programming systems are quite brilliant so the fact that they haven't solved certain issues is significant.)
> I think there are actually conceptual advantages to thinking of the universe functionally(as a tail-recursive function with all the "state" contained in the parameters), in case a method for time travel is ever developed.
Talk about premature optimization, not to mention the bogus assumption that a universe with time travel can't be stateful.
> Many pure functions are easier to think about than their impure equivalents, but it's certaintly not the case the all pure functions are easier to think about than their impure equivalents.
I disagree. Most cases of the pure function being harder to think about than the impure equivalent are a result of either demanding impure semantics from a pure function(pure functions aren't always the best choice for implementation) or bad programming. I think that even programs that are best implemented statefully such as databases are easier to think about if they are defined conceptually in a pure way(as functions taking an additional parameter to represent the database state when it is called) regardless of how they are actually impelmented.
> And, because pure functions have no state, many pure functions have to drag along state through their parameters that they don't need/use but that their callees need/use.
I don't understand this argument. Calling another function on data from their parameters is the way functions need/use their parameters.
> "the appropriate response"? Sorry, I have work to do, work that doesn't include making advocates of functional programming happy, let alone spending time on things that they haven't been able to do.
I'm not saying that you have some sort of obligation to make it possible to more understandably solve some problem purely. However, as I am one of those functional programming advocates, I think that you would be helping yourself by solving problems purely when impure semantics are not a necessary requirement of the problem(I would also expect that fewer problems than you might think require impurity). What I meant by what you quoted is not that you specifically should make a better functional language, but that flaws in the existing languages are not necessarily a condemnation of the concept of pure functions.
> (Some of the developers of functional programming systems are quite brilliant so the fact that they haven't solved certain issues is significant.)
Significant, but hardly an indication that those issues are unsolvable. C was developed by quite brilliant people, but there were many issues they did not solve.
> Most cases of the pure function being harder to think about than the impure equivalent are a result of either demanding impure semantics from a pure function(pure functions aren't always the best choice for implementation)
So much for the claim that purity is always easier to understand....
>> And, because pure functions have no state, many pure functions have to drag along state through their parameters that they don't need/use but that their callees need/use.
> I don't understand this argument. Calling another function on data from their parameters is the way functions need/use their parameters.
Callees provide a service. I don't care how they provide said service, but if they're "stateful", functional programming exposes that.
> However, as I am one of those functional programming advocates, I think that you would be helping yourself by solving problems purely when impure semantics are not a necessary requirement of the problem(I would also expect that fewer problems than you might think require impurity).
Read up the thread. I'm a believer, and I'm telling you that the way that fp folk advocate is counter-productive. (Telling people that they shouldn't reject fp because some future language might be useful for their problem is especially dumb.)
> C was developed by quite brilliant people, but there were many issues they did not solve.
C wasn't developed by folks who were trying to introduce a new type of programming language. C was, in some sense, an afterthought for them because their argument was about systems building, not programming languages. Also, it was a different world then - C didn't really have competitors.
While FP can be a fantastic way of programming, FP advocates are mindbogglingly ignorant of people and programming in the real. (Perhaps the ability to write small programs for some non-trivial problems is an obstacle to understanding.)
"the real world (and machines) are stateful/not functional"
This could be argued as being totally wrong philosophically, and is certainly not a proved statement.
I could say that state is only the creation of the human mind in a world that is essentially made of movement, in order to understand it and quantize it. Even matter at the lowest level is the movement or particles, almost as much as it is the particles themselves.
This point is not without link to the current argument about functional/imperative programming, and certainly shows that your view of the matter, while not false, is certainly narrow minded.
