6.7.1 Runtime Systems

Stand-alone applications containing debugged Prolog code and destined for end-users are typically packaged as runtime systems. No SICStus license is needed by a runtime system. A runtime system has the following limitations:

• No top-level. The executable will restore a saved-state and/or load code, and call user:runtime_entry(start). Alternatively, you may supply a main program and explicitly initialize the Prolog engine with SP_initialize(). break/0 and require/1 are unavailable.
• No debugger. debugging, debug and debugger_print_options have no effect. Predicates annotated as [development] in the reference pages are unavailable.
• Except in extended runtime systems: no compiler; compiling is replaced by consulting. Extended runtime systems do provide the compiler.
• The discontiguous_warnings, single_var_warnings, redefine_warnings, and informational Prolog flags are off by default, suppressing warnings about clauses not being together, singleton variables, queries and warnings about name clashes and redefinitions, and informational messages. Note that they can be switched on though, to enable such warnings, queries and messages.
• No profiler or coverage analysis. The predicates profile_reset/0, profile_data/1, print_profile/[0,1] coverage_data/1, and print_coverage/[0,1] are unavailable. The Prolog flag profiling is unavailable.
• No signal handling except as installed by SP_signal().

It is possible to tell a runtime system to start a development system instead, for debugging purposes. See Debugging Runtime Systems for details.