[摘录]Programming Languages Support Decomposing Problems

From Python 2.6.4 documenation

 

Programming languages support decomposing problems in serveral different ways:

1.  Most programming languages are procedural: programs are lists of instructions that tell the computer what to do with the program's input. C, Pascal, and even Unix shell are procedural languages.
2. In declarative languages, you write a specification efficiently. SQL is the declarative language you are most likely to be familiar with; a SQL query describes the data set you want to retrieve, and the SQL engine decides whether to scan or use indexes, which subclauses should be performed first, etc.
3. Object-Oriented programs manipulate collections of object. Objects have internal state and support methods that query or modify this internal state in some way. Smalltalk and Java are Object-Oritented languages. C++ and Python are languages that support Object-Oriented programming, but don't force the use of Object-Oriented features.
4. Functional programming decomposes a problem into a set of functions. Ideally, functions only talk inputs and proceduce ouputs, and don't have any internal state that affects the output proceduced for a given input. Well-know function languages include the ML family(Standard ML, OCaml, and other variants) and Haskell.