Algebra.ZeroTestable

Maybe the naming should be according to Algebra.Unit: Algebra.Zero as module name, and query as method name.

Checks if a number is the zero element. This test is not possible for all C types, since e.g. a function type does not belong to Eq. isZero is possible for some types where (==zero) fails because there is no unique zero. Examples are vector (the length of the zero vector is unknown), physical values (the unit of a zero quantity is unknown), residue class (the modulus is unknown).