1. A function exchange system comprising: a network communication device; a non-transitory computer-readable medium that stores: processor-executable instructions; and a plurality of function module records, wherein each of the function module records includes (i) a function module identifier, (ii) a function module, and (iii) an indication of a function performed by the function module; and processor hardware that executes the processor-executable instructions, wherein the processor-executable instructions include: for each of the function module records, receiving, via the network communication device, the function module from a corresponding one of a plurality of producing developers; generating an interface to receive a selection of one of the function module records by a consuming developer for incorporation into a state template of a first application under development by the consuming developer; in response to receiving the selection of the one of the function module records, providing the function module identifier of the selected one of the function module records to the consuming developer prior to the consuming developer distributing the first application via a digital distribution platform; receiving, via the network communication device, a function module request from a copy of the first application downloaded onto a user device via the digital distribution platform, wherein the function module request includes a first function module identifier that uniquely identifies a first function module record of the function module records; in response to receiving the function module request, transmitting, via the network communication device, the function module of the first function module record to the user device; maintaining a hierarchy of functions that each have a textual description, wherein: for each of the function module records, the indication of the function performed by the function module corresponds to one of the functions of the hierarchy; and the hierarchy is used in the interface to organize the function module records for selection by the consuming developer; and transmitting to the consuming developer, via the network communication device, a library for inclusion in the first application, wherein the library includes instructions to: store the function module; execute the function module; and present display data generated by execution of the function module, wherein the display data is presented in an area reserved for the function by the state template.