In a fault-tolerant parallel computer, a functional programming model can facilitate distributed checkpointing, error recovery, load balancing, and graceful degradation. Such a model has been implemented on the Draper fault-tolerant parallel processor (FTPP). When used in conjunction with the FTPP's fault-detection and masking capabilities, this implementation results in a graceful degradation of system performance after faults. Three graceful degradation algorithms are presented. A user interface has been implemented which requires minimal cognitive overhead by the application programmer, masking such complexities as the system's redundancy, distributed nature, variable complement of processing resources, load balancing, fault occurrence, and recovery. This user interface is described and its use demonstrated.