A method performed by one or more processing devices includes receiving a request to generate a computer program; generating, in response to receiving the request, a first user interface that when rendered on a display device renders: one or more first visual representations of one or more first fields of the first resource; and one or more second visual representations of one or more second fields of the second resource; receiving, through the first user interface, a selection of: at least one of the one or more first visual representations; and at least one of the one or more second visual representations; receiving, through a second user interface, data specifying the one or more operations; and updating, based on the received data, the computer program with one or more third instructions to perform the one or more operations.