Would prefer to use an equality test

There is a problem with doing that in Alice. 

Alice has only one numeric type named Number.

It is not an integer type.

Therefore, the value of index can have a fractional part.

Although none of the code would be expected to produce a fractional part, general accuracy problems can result in very small fractional parts.

Testing two values of type Number for absolute equality

• Is highly unreliable and
• Will often result in a false result even though the two values are equal for all practical purposes