This paper describes an implementation language and synthesis system for automatically generating latency insensitive synchronous digital designs. These designs decouple behavioral correctness from design performance by allowing any sub-component to dynamically stall without changing correct system activity. This is accomplished by imposition of global invariants and use of local control in the form of Synchronous-Elastic Flow (SELF) networks, which are directly synthesized. This design description format reduces the complexity of implementing correct SELF networks and does not require pre-design of a correct conventional synchronous design. The design description is a specialized guarded atomic action language which is particularly suited for succinctly describing SELF designs. We present the language syntax, semantics and synthesis techniques illustrated by the design of a latency tolerant cache controller.