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Why would we need to limit our programming language abstractions to how the machines work underneath? Are there some stateful objects running around in the hard

by hopia 7y ago

Why would we need to limit our programming language abstractions to how the machines work underneath? Are there some stateful objects running around in the hardware? Just because the abstractions are detached from the hardware doesn't make these design patterns useless.

yxhuvud 7y ago
It is nice to have a connection between abstractions and hardware, because it makes it easier to reason about performance, which in turn makes it easier to achieve great performance. Now, not everybody actually need great performance, so some distance between hardware and abstraction is ok, but the amount depends on the use case.
- hopia 7y ago
  Well, I agree, that's why we have both low and high level languages. High level languages, setting you free from the actual constraints of the underlying machine, allow you to define abstractions that can increase productivity greatly - that's their whole point of existence. I mean I don't see people complaining how you don't need to manually manage memory in SQL expressions.
  - pkolaczk 7y ago
    > I mean I don't see people complaining how you don't need to manually manage memory in SQL expressions. Well, they don't complain about not having to manually control the low-level bits of query execution, but later they frequently complain about performance problems. And then they add hints, setup buffer sizes, indexes, etc. Also, Rust (and to some degree C++) shows that you can have both very high-level, productive abstractions and low-level control. They call that zero-cost abstractions. The price to pay is a steeper learning curve, but not actual productivity or final performance. This is the most exciting part about Rust actually. I know how to write Kotlin, Scala, Java or C# code that's close in performance to C or C++. But this will be ugly, unsafe and hard to maintain, non-idiomatic code. Rust gives ability to write code that has almost Python-like expressivity but is still fast as if it were hand-optimised loops and pointers.
    - hopia 7y ago
      I'm not sure what your point is. I feel we may have a different idea of what very high level abstraction means in programming languages. Just about everything in software engineering is a compromise of sorts. Not knowing Rust or C++, I doubt they're as high level as something like Haskell or domain specific languages like SQL. Are monads first class citizens on C++? Type classes? Generalized Algebraic Data types? Parametric polymorphism & pattern matching? And so on. Would you really achieve the same amount of type level guarantees, equally concise control flow and concurrency on C++ with an equal amount of lines of code as would be possible on Haskell? If not, then there obviously is a productivity penalty. Just like on Haskell there is that performance penalty for not being able to drop down close to the metal. From what I can tell, these languages are not aiming to be very high abstraction level languages but instead solid systems level languages with some convenient abstractions and design patterns baked in from higher level languages. Sticking only to some zero-cost abstractions limits how high level abstractions it is possible to bring to the language. This in turn limits productivity.
      - pkolaczk 7y ago
        Rust is very strong in its ability to build extremely powerful abstractions. With built-in compile-time procedural metaprogramming I could risk a statement that in some domains it may be actually even higher level than Haskell. Maybe its type system can't prove all the same guarantees as Haskell, but on the other hand, Haskell can't prove some guarantees that Rust can. They offer different set of abstractions with some overlap (e.g. first class type classes and ADTs). If is really hard to say which one is higher level. They are just different. Anyway, type safety is not the same as productivity. If it was, then nobody would use Python or Ruby and everybody would use Idris. I became much more productive quickly in Rust than Haskell.
        hopia 7y ago
        Interesting, what kind of guarantees does Rust give that Haskell's abstractions cannot do? Haskell also has metaprogramming in terms of Generics and Template Haskell, allowing you to create custom DSLs and such. Sadly, it kind of leads to pretty ridiculous compile times and mixed editor support so I'm trying to avoid that. We should remember productivity is really subjective and not the same thing as high level abstractions. We're typically the most productive on the language we have the most exposure to, whatever it may be.
pkolaczk 7y ago
Sure, I didn't say "useless". The post I was responding to was worded in such a way as if FP was the only suitable paradigm everybody should be using. FP is a nice and useful abstraction, but in some areas it is just too inefficient and despite all the great compiler progress of the last decade, it is still not there yet. FP languages are not in the same problem domain as system programming languages, so claiming FP should replace Rust is just ridiculous (and as a side note: Rust borrows many things from Haskell/Scala as well, so some FP is there).

by hopia 7y ago

yxhuvud 7y ago

It is nice to have a connection between abstractions and hardware, because it makes it easier to reason about performance, which in turn makes it easier to achieve great performance. Now, not everybody actually need great performance, so some distance between hardware and abstraction is ok, but the amount depends on the use case.

hopia 7y ago
Well, I agree, that's why we have both low and high level languages. High level languages, setting you free from the actual constraints of the underlying machine, allow you to define abstractions that can increase productivity greatly - that's their whole point of existence. I mean I don't see people complaining how you don't need to manually manage memory in SQL expressions.
- pkolaczk 7y ago
  > I mean I don't see people complaining how you don't need to manually manage memory in SQL expressions. Well, they don't complain about not having to manually control the low-level bits of query execution, but later they frequently complain about performance problems. And then they add hints, setup buffer sizes, indexes, etc. Also, Rust (and to some degree C++) shows that you can have both very high-level, productive abstractions and low-level control. They call that zero-cost abstractions. The price to pay is a steeper learning curve, but not actual productivity or final performance. This is the most exciting part about Rust actually. I know how to write Kotlin, Scala, Java or C# code that's close in performance to C or C++. But this will be ugly, unsafe and hard to maintain, non-idiomatic code. Rust gives ability to write code that has almost Python-like expressivity but is still fast as if it were hand-optimised loops and pointers.
  - hopia 7y ago
    I'm not sure what your point is. I feel we may have a different idea of what very high level abstraction means in programming languages. Just about everything in software engineering is a compromise of sorts. Not knowing Rust or C++, I doubt they're as high level as something like Haskell or domain specific languages like SQL. Are monads first class citizens on C++? Type classes? Generalized Algebraic Data types? Parametric polymorphism & pattern matching? And so on. Would you really achieve the same amount of type level guarantees, equally concise control flow and concurrency on C++ with an equal amount of lines of code as would be possible on Haskell? If not, then there obviously is a productivity penalty. Just like on Haskell there is that performance penalty for not being able to drop down close to the metal. From what I can tell, these languages are not aiming to be very high abstraction level languages but instead solid systems level languages with some convenient abstractions and design patterns baked in from higher level languages. Sticking only to some zero-cost abstractions limits how high level abstractions it is possible to bring to the language. This in turn limits productivity.
    - pkolaczk 7y ago
      Rust is very strong in its ability to build extremely powerful abstractions. With built-in compile-time procedural metaprogramming I could risk a statement that in some domains it may be actually even higher level than Haskell. Maybe its type system can't prove all the same guarantees as Haskell, but on the other hand, Haskell can't prove some guarantees that Rust can. They offer different set of abstractions with some overlap (e.g. first class type classes and ADTs). If is really hard to say which one is higher level. They are just different. Anyway, type safety is not the same as productivity. If it was, then nobody would use Python or Ruby and everybody would use Idris. I became much more productive quickly in Rust than Haskell.
      - hopia 7y ago
        Interesting, what kind of guarantees does Rust give that Haskell's abstractions cannot do? Haskell also has metaprogramming in terms of Generics and Template Haskell, allowing you to create custom DSLs and such. Sadly, it kind of leads to pretty ridiculous compile times and mixed editor support so I'm trying to avoid that. We should remember productivity is really subjective and not the same thing as high level abstractions. We're typically the most productive on the language we have the most exposure to, whatever it may be.

pkolaczk 7y ago

Sure, I didn't say "useless". The post I was responding to was worded in such a way as if FP was the only suitable paradigm everybody should be using. FP is a nice and useful abstraction, but in some areas it is just too inefficient and despite all the great compiler progress of the last decade, it is still not there yet. FP languages are not in the same problem domain as system programming languages, so claiming FP should replace Rust is just ridiculous (and as a side note: Rust borrows many things from Haskell/Scala as well, so some FP is there).