问题
I'm trying to understand the difference between imperative and declarative paradigms, because I have to classify Visual Basic. NET in the different paradigms. Beyond object-oriented, I guess it's also imperative or declarative. If someone could help me explaining how I realized I would appreciate
回答1:
Imperative code is procedural: do this, then this, then that, then the other, in that order. It's very precise and specific in what you want. Most languages that we use for building end-user applications are imperative languages, including VB.Net. Language structures that indicate an imperative language include if blocks, loops, and variable assignments.
Declarative code just describes the result you want the system to provide, but can leave some actual implementation details up to the system. The canonical example of a declarative language is SQL (though it has some imperative features as well). You could also consider document markup languages to be declarative. Language structures that indicate a declarative language include set-based operations and markup templates.
Here's the trick: while VB.Net would traditionally be considered imperative, as of the introduction of LINQ back in 2008, VB.Net also has significant declarative features that a smart programmer will take advantage of. These features allow you to write VB.Net code that looks a lot like SQL.
回答2:
I classify CSharp/VB as Multi-paradigm. They are imperative (IF,FOR,WHILE), declarative (LINQ) object-oriented and functional(Lambda). I think that in today landscape there are no more pure languages, they have a bunch of bits of several paradigms.
"The idea of a multiparadigm language is to provide a framework in which programmers can work in a variety of styles, freely intermixing constructs from different paradigms" http://en.wikipedia.org/wiki/Timothy_Budd
回答3:
VB.NET never required LINQ to be considered declarative. In my understanding, declarative means that a programming language can speak English, i.e. business logic is written exactly as requirements say. The actual implementation may vary. This is called domain driven design (DDD) in some schools of thought.
For this matter, any object oriented language can be seen as declarative. Which does not take away its imperative functions - those are used to make it as declarative as you want it. And this is power behind properly implemented OO concepts, with a concrete task in mind.
来源：https://stackoverflow.com/questions/22967615/imperative-vs-declarative-code