Systems and methods for iterating between a graphical user interface and an expression for data visualization. Exemplary methods include: evaluating an expression at a client, the expression associated with a component, the evaluating determining data is to be retrieved from a server; running at least part of the expression at the server, the server determining input from the client is to be used to process the at least part of the expression; processing the modified expression at the client, the processing including getting the input at the client and providing the input to the server; and resuming the running of the at least part of the expression at the server, the resuming including running the at least part of the expression using the input to produce retrieved data and giving the retrieved data to the client.