b_main.chr

:- module(opmain, [run/3]).
:- use_module(prelude).
:- use_module(opslib, [fun '<>>'/2, op(500, yfx, '<>>')]).
:- chr_constraint run/3.

% The custom '<>>' infix from opslib (X <>> Y = X*10 + Y) is only visible
% because of the import. Without it, '<>>' would not be a known operator.
run(X, Y, R) <=>
    R is X <>> Y.