Synchronous Operations as First-Class Values

Message passing via channels is an interprocess communication (IPC) mechanism found in several concurrent languages, such as CSP, occam, and Amber. Channel I/O operations are synchronous, and include a powerful selective I/O operation. Because this IPC mechanism is provided in an "operation-oriented" fashion, only procedural abstraction techniques can be used in the structuring of the communication/synchronization aspects of a system.