:- module main. :- interface. :- use_module io. :- pred main(io.io::di, io.io::uo) is det. :- implementation. :- use_module string. :- use_module exception. :- import_module int. :- import_module list. :- pred get_int(string::in, int::out, io.io::di, io.io::uo) is det. get_int(Name, Out, !IO) :- io.write_string("Please enter ", !IO), io.write_string(Name, !IO), io.nl(!IO), io.read_line_as_string(LineResult, !IO), ( ( LineResult = io.error(_) ; LineResult = io.eof ), exception.throw(exception.software_error("IO Error")) ; LineResult = io.ok(Line), ( if string.to_int(string.strip(Line), Int) then Out = Int else io.write_string("Not an integer.\n", !IO), get_int(Name, Out, !IO) ) ). :- pred print_speed(int::in, int::in, io.io::di, io.io::uo) is det. print_speed(Speed, Hour) --> io.write_string("Hours: "), io.write_int(Hour), io.write_char(('\t')), io.write_string("Distance: "), io.write_int(Distance), io.nl, { Distance = Hour * Speed }. main(!IO) :- get_int("speed", Speed, !IO), get_int("hours", Hours, !IO), list.foldl(print_speed(Speed), 0 .. Hours, !IO).