I want to fix programming • Hacker News Board

Re: I want to fix programming

#111

Post by jamesrcole » Wed, Jan 25, 2012, 7:07 AM UTC

jerf wrote: post #55

So, over the years I've played with many things that claim to be "declarative", and here's why I now shy away from them like the plague. There's no such thing as "declarative". No matter what you type into the computer, at some point it's going to turn into instructions that do the thing you want done. Trying to create a declarative language is a way of making it extraordinarily opaque as to what the machine is actua…

I don't think there's any inherent problem with stuff being declarative. We just need the software to be smart enough to handle it well. We might have a long way to go till we can do this effectively.

I'd suggest looking at 'declarative' from the point of view of delegation (not in the technical sense, but the usual sense of getting someone else to do a task for you). Ideally you want to specify what you want to be done and you shouldn't care about how it's done. Software is meant to be a labor saving device.

I assume you're ok with the idea of delegating tasks to people. If the software was smart enough I think it'd reasonable to delegate to it as well.

Re: I want to fix programming

#112

Post by aphyr » Wed, Jan 25, 2012, 7:11 AM UTC

giberson wrote: post #74

So imagine you define some amazing PSL (Problem/Solution Language). It let's you "Code" by defining the problem and solution, ie: Define SORT: Given SET(x), Find SET(y) Where [For i in y] y[i]>y[i-1]. So now you're feeling all giddy because this amazing language is so awesome--you didn't have to specify how to do something step by step. You just declared what you wanted, and it gave it to you. Fantastic. But then, no…

No. You're thinking imperatively. The pure form would express something like: "given the property sorted(s) defined in this way, let s be a set such that for all elements e of s, e is an element of the program input. Then let the output of the program be the list l such that sorted(l) is true.

Re: I want to fix programming

#113

Post by buff-a » Wed, Jan 25, 2012, 7:17 AM UTC

ChristianMarks wrote: post #64

The problems the OP wants to solve are formally undecidable and reducible to the halting problem. 1. Given a formal specification, find a program that meets the specification. 2. The apparently simpler problem of checking whether a given program meets a specification. Both are undecidable. That said, there is an extensive literature on practical approaches to this problem. They generally suffer from intractability. h…

The thing about the halting problem, though, is that it doesn't say "You can't write a program that can determine if another program will terminate". It says "You can't write a program that can determine if any other program will terminate."

Case in point: Resharper will tell me "This function never returns" in cases where it obviously wont return, and also offer to simplify methods that only ever return a single value despite what looks like a complex set of if-statements.

So, if it is possible to write a program to determine if a specific subset of all possible programs will terminate, is it possible to write a program that can generate a subset of all possible programs from a specific subset of all possible specifications?

I can't be perfect. But might it be useful?

Re: I want to fix programming

#114

Post by cr4zy » Wed, Jan 25, 2012, 7:19 AM UTC

jamesrcole wrote: post #111

jerf wrote: post #55

So, over the years I've played with many things that claim to be "declarative", and here's why I now shy away from them like the plague. There's no such thing as "declarative". No matter what you type into the computer, at some point it's going to turn into instructions that do the thing you want done. Trying to create a declarative language is a way of making it extraordinarily opaque as to what the machine is actua…

I don't think there's any inherent problem with stuff being declarative. We just need the software to be smart enough to handle it well. We might have a long way to go till we can do this effectively. I'd suggest looking at 'declarative' from the point of view of delegation (not in the technical sense, but the usual sense of getting someone else to do a task for you). Ideally you want to specify what you want to be d…

Search is declarative and works well.

Re: I want to fix programming

#115

Post by parbo » Wed, Jan 25, 2012, 8:07 AM UTC

dmitriy_ko wrote: post #101

munificent wrote: post #85

Earlier quoted context omitted.

> What if you created a declarative language which allows you to override the algorithms in a functional/imperative? We have that. They're called libraries. If I need to sort a collection, I don't write an imperative chunk of code, I just do: sort(myCollection) Looks pretty declarative to me.

The issue here is that function definition doesn't tell what the function does. So you may have hundred implementations of sorting algorithms in different libraries, and neither compiler nor the IDE know that they all do the same thing. So when you write sort(myCollection) you are still referring to one particular set of instructions. The system parent poster envisions (the way I understand it) would be along those l…

Interfaces, polymorphism and templates?

Re: I want to fix programming

#116

Post by yason » Wed, Jan 25, 2012, 8:30 AM UTC

As it happens, computer science is exactly about those rigid steps of how to get a computer do bigger things. If you could express what you want, you could replace considerable part of Knuth's books by referring to "just sort these numbers for me", leaving the "how" to the computer.

Bridges don't get built because some guys "wants to go see the other shore". Bridges get built by rigorous design and constructed a rivet by rivet or bolt by bolt. Then you can go see the other shore.

For most part, we've come a long way in programming. Sorting has many reasonable algorithmic approaches well-studied and as a result of that in almost any language you can already say sort() and have some stuff sorted. I don't particularly need to know that Python uses timsort, it just sorts. Of course, I can study sorting in detail if I want to and possibly discover something novel.

Why programming never gets easy is that by solving existing problems we accumulate newer, more complex problems and interactions. Programming will always be difficult because we automate anything that's no longer difficult.

The "Sort these" example is not programming, it's something else that potentially builds on programming. Type some stuff into Matlab and watch your computer sort out difficult stuff for you and do the calculations in parallel in highly efficient manner using Cuda. It's not programming, it's using a machinery that has been programmed to interpret certain classes of the user's wishes and take care of all the physical steps required to finish the desired computation. You still can't ever take a blanko computer, ask it to sort stuff, watch it figure out how and call that programming.

Re: I want to fix programming

#117

Post by nnq » Wed, Jan 25, 2012, 8:41 AM UTC

Why not fix the problem with 2 languages?

Let me explain. You would have:

1. a language for your actual code - the real code of your application (imagine an application programmed in Python or C++)

2. a language to concisely describe what the code does - the code for your "tests" (imagine the tests written in a simplified Haskell or some dialect of mathematical language)

There would be different constrains for the two languages, as language (2) would not have to be efficient or portable or any other requirements you can imagine, it should just be very concise, to allow to describe in a couples of lines what 100 or 1000 lines of language (1) code do.

And it would be very different from just writing very granular tests: the program could be run in "debug" mode, with the language (2) tests or executable-descriptions of a function running after every function call (very slow but still working), and in a "real" mode in the client computer or when profiling and optimizing for speed. You could still have regular test and language (2) could be much simpler than something like Haskell because it would not need have fast execution and it will only be written in short snippets that could be proven correct by "pen & paper" or "mind running".

[minor edit for spelling and paragraphs]

Re: I want to fix programming

#118

Post by nandemo » Wed, Jan 25, 2012, 9:02 AM UTC

ryanbraganza wrote: post #12

jng wrote: post #4

Earlier quoted context omitted.

OP here. It's not just Prolog, but indeed Prolog is the closest thing now.

How is it not just prolog? At the very least, a constraint programming language would be a good basis to start with here. http://en.wikipedia.org/wiki/Constraint_programming

I don't think there's any existing programming language that does what OP wants.

But Prolog is far from the last word on the subject. For one, it is basically untyped. There are dependently-typed programming languages that can express non-trivial properties via types, which the compiler can check (see ezyang's example).

Re: I want to fix programming

#119

Post by jacktoole1 » Wed, Jan 25, 2012, 9:58 AM UTC

nandemo wrote: post #110

jerf wrote: post #55

So, over the years I've played with many things that claim to be "declarative", and here's why I now shy away from them like the plague. There's no such thing as "declarative". No matter what you type into the computer, at some point it's going to turn into instructions that do the thing you want done. Trying to create a declarative language is a way of making it extraordinarily opaque as to what the machine is actua…

> Trying to create a declarative language is a way of making it extraordinarily opaque as to what the machine is actually going to do. It looks great in four lines, it crashes and burn on any real sized problem, Erlang, Haskell and Ocaml are examples of declarative languages, and they all have been used to solve very real-sized problems: telecommunication switches, compilers, trading systems, a window manager, etc. I…

I love OCaml, but I would hardly call it a declarative language. You still describe the steps to perform an algorithm, rather than the result of the algorithm. The article poster references Haskell and explicitly says "The functional approach brings indeed several improvements over regular imperative or object-oriented programming. But still it’s not the solution."

Re: I want to fix programming

#120

Post by [deleted] » Wed, Jan 25, 2012, 10:11 AM UTC

raganwald wrote: post #10

Dear Jon: What you have is fabulous and immediately useful: You are describing a language for describing constraints on the results of computer programs. In other words, you can express the correctness of a computer program and check whether a program is, in fact, correct. It’s true that IF a sufficiently smart compiler could infer a working program from the definition of correctness, no further “programming” would b…

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