A complex has a Cartesian structure, with a real part and an imaginary part each of which is a real. The parts of a complex are not necessarily floats but both parts must be of the same type: either both are rationals, or both are of the same float subtype. When constructing a complex, if the specified parts are not the same type, the parts are converted to be the same type internally (i.e., the rational part is converted to a float). An object of type (complex rational) is converted internally and represented thereafter as a rational if its imaginary part is an integer whose value is 0.
For further information, see Section 18.104.22.168 (Sharpsign C) and Section 22.214.171.124.4 (Printing Complexes).