Listloop : Enumerating the Elements of a List

Listloop enumerates and returns the elements of a list one by one.

In other words, at each step of the iteration, listloop takes a smaller chunk of the list, and returns its first element. The execution ends once the list is exhausted.

Here, listloop enumerates a list and returns its items one by one.

1. At each step of the loop, EachtTime evaluates collect.

2. Collect stores the items of the list.

3. • The first input of Finally returns the last value of the iteration.
   • Its second input returns the result of collect.

The default value of the " by " optional input is a cdr¹ .

This means that, at each loop, listloop returns :

1. the first element of the list,

2. and then, the first element of the remaining chunk,

3. and so on.

In Lisp, this means that listloop returns successive cadrs¹ .

"By" can be replaced by another function meant to return a smaller chunk of a list, such as : cddr ¹ or nthcdr for instance.

It can be either a function box on "lambda" mode, or a function name.