op/2¶

op(+ Precedence,+ Type,+ A)* is iso

Defines the operator A or the list of operators A with type T (which must be one of xfx, xfy,yfx, xf, yf, fx or fy) and precedence P (see appendix iv for a list of predefined operators).

Note that if there is a preexisting operator with the same name and type, this operator will be discarded. Also, , may not be defined as an operator, and it is not allowed to have the same for an infix and a postfix operator.