On this page:
5.1 Processor Types
transport-processor/  c
protocol-processor/  c
7.4

5 Thrift Processor Support

Support for Thrift processor contracts.

Examples:
> (require thrift)
> (define/contract (my-processor in out)
    transport-processor/c
    #f)

5.1 Processor Types

 (require thrift/processor/common) package: thrift