Interfaces

The std module defines several interfaces. They are described in this section. Note that a class may implement multiple interfaces.

Interface Sequence<T>

An object that implements Sequence can be used as a read-only sequence. The interface includes the following operations:

length() as Int

Return the length of the sequence.

sequence[n] (Sequence<T>[Int] ⇒ T)

Return the element at the specified index. The first element has index 0, the second 1, etc.

Note: Negative index values need not be supported.

Array and Str implement Sequence. Note that Array objects are mutable.

Interface Iterable<T>

Iterable objects provide the iterator method:

iterator() as Iterator<T>

Return an iterator that iterates over all the objects in a composite object.

Str, Range, Array, Map, Set and Stream objects implement Iterable.

Interface Iterator<T>

An object that supports the Iterator interface performs an iteration over the items of a composite object. It provides these methods:

hasNext() as Boolean

Return a boolean indicating whether there are additional objects in the iteration.

next() as T

Return the next object in the iteration. The iterator interface does not specify the order in which objects are returned, but many iterable types, such as Array, guarantee a specific iteration order.

Interface Comparable<T>

o < x (Comparable<T> < T ⇒ Boolean)

o > x (Comparable<T> > T ⇒ Boolean)

A Comparable object supports comparisons using < and >.

Interface Addable<OT, RT>

o + x (Addable<OT, RT> + OT ⇒ RT)

An instance that implements Addable supports the + operation. The operand and result types are derived from the type arguments.

Interface Multipliable<OT, RT>

o * x (Multipliable<OT, RT> * OT ⇒ RT)

An instance that implements Multipliable supports the * operation. The operand and result types are derived from the type arguments.