Creating external types: second example

Mosel defines the types integer, real and boolean on which arithmetic operations may be used. By creating modules it is possible to add other types, such as complex numbers, to this list. In the previous chapters we have already seen an example of how to define a new type in a module, but this new type task was not suited to be used with arithmetic operations. In this chapter we shall therefore give another example of the definition of a type, this time of a type to which such operations may sensibly be applied.