1. A process comprising: using a first GUI component of a graphical user interface (GUI) generated using GUI logic of a client computer, receiving an expression comprising a first expression portion and a second expression portion, wherein the GUI logic is programmed to receive in the GUI component the first expression portion that specifies one or more market instruments and one or more mathematical operations involving at least one of the one or more market instruments and to receive in the GUI component the second expression portion that specifies a method that is to be applied based on the first expression portion; using a time series generator programmed with a set of computer-executable instructions, constructing and returning a time series; using a parsing module in an application server, parsing the expression to generate an in-memory representation of the time series in computer memory and evaluating the expression to generate the time series at least in part by: using the time series generator, retrieving intermediate information that has been previously generated from one or more mathematical operations performed on one or more sets of data values and stored in a data repository server for subsequent use; if the data repository server does not contain the intermediate information that has been previously generated, then: using the time series generator, retrieving the one or more sets of data values from the data repository server; using the time series generator, performing the one or more mathematical operations on the one or more sets of data values to execute one or more modifications to each data value of one or more sets of data values that represent the at least one of the one or more market instruments, wherein the one or more sets of data values are stored using a data repository server, to generate the intermediate information at least in part by modifying each data value of the one or more sets of data values and storing the generated intermediate information in the data repository server for subsequent use in another time series generation; using a method logic module within the application server, applying a first method to the intermediate information; using the application server, storing the time series in computer data storage on the data repository server, and causing displaying the time series in a content pane of the same GUI located on the client computer; wherein the process is performed by one or more computing devices.