A view to a collection

Databases have views. A database view works just like a table; however, the table never exists. It is just an illusion. A view is only a stored query, which is run when the view name is referenced:

Mysql> CREATE VIEW first_last AS SELECT first_name, last_name FROM NAMES WHERE last_name LIKE ('k%');
mysql> SELECT first_name FROM first_last;

The view first_last query is backed by the result set of a query, on a real table, NAMES. We can select only the columns of interest and apply some transformations on them.

Scala collection views are similar. We will soon be giving a close look to functional transformation. However, to get a taste, the following is an example:

We need to assign a temporary password to a user. We have a list of randomly generated passwords. We need to pick one.

Our validation rules are:

1. A password cannot be empty.

2. It must have at least an uppercase letter.

3. It should have a numeric character.

4. It must have a special character.

5. It must have five or more...