6.5  Executing an ECLⁱPS^e Goal From Tcl

An ECLⁱPS^e predicate can be invoked from the Tcl side using the remote ECLⁱPS^e predicate call (ec_rpc) facility. This should be the main method of interacting and communicating with ECLⁱPS^e in the remote interface. Information can be sent to ECLⁱPS^e via bindings for (input) arguments when the call is made; and results returned from ECLⁱPS^e via the bindings made to (output) arguments:

ec_rpc goal ?format?

Remote ECLⁱPS^e predicate call. It calls goal in the default module. The goal should be simple in the sense that it can only succeed, fail or throw. Any choice-points the goal leaves will be discarded.

Calls to ec_rpc can be nested and can be used from within Tcl queue event handlers. However, an ec_rpc cannot be issued while ECLⁱPS^e side has control.

If no format argument is given, the goal is assumed to be in ECLⁱPS^e syntax. If a format argument is provided, the ECLⁱPS^e goal is constructed from goal and format, according to the conversion rules explained in section 5.8.

On success, ec_rpc returns the (possibly more instantiated) goal as a Tcl data structure (in EXDR format), otherwise "fail" or "throw" respectively.