关于本章

在前面章节已经介绍了repetition，本章对它进行详细描述。

下面是实现repetition("重复执行某个computation")的两种方式：

• iteration
• recursion

无处不在的repetition

Traverse on structure

参见Relation-structure-computation\Structure\Computation-on-structure章节。

TODO

需要增加一些例子。

Recursion and functional programming

在functional programming一般使用recursion来实现repetition，关于此，在下面文章中有描述:

wikipedia Recursion (computer science)

Some functional programming languages do not define any looping constructs but rely solely on recursion to repeatedly call code.

wikipedia Functional programming

Iteration (looping) in functional languages is usually accomplished via recursion. Recursive functions invoke themselves, allowing an operation to be performed over and over until the base case is reached.

Iteration VS recursion

两种都能够实现repetition。

Iteration的实现依赖于Iteration statements

NOTE: 关于Iteration statements，参见:

1) C++: cppreference Iteration statements

2) Python:

8.3. The for statement¶

8.2. The while statement¶

Recursion的实现依赖于recursive function

当所处的环境无法使用Iteration statements的时候，则只能够通过Recursion来实现repetition:

1) 有的programming language并没有提供iteration statement，比如Lisp，因此，它们只能使用recursion来实现repetition。

2) C++ TMP