# OclSummable

## `OclSummable`

The type OclSummable defines the sum and zero operations used by the Collection::sum iteration. Only types that provide derived sum and zero implementations may be summed.

conformsTo `OclAny`

Operations

`sum(that : OclSelf[?]) : OclSelf[?]`

Return the sum of self and that.

The sum operation should be associative.

`zero() : OclSelf[?]`

Return the ‘zero’ value of self to initialize a summation.

zero().sum(self) = self.