syntax grammar
mercury:
(term end) *
semantic grammar
mercury:
module_decl
interface_decl
export_decl*
implementation_decl
implementation_program*
end_module_decl?
export_decl:
import_module_decl
|use_module_decl
|include_module_decl
|pred_decl
|mode_decl
|func_decl
|type_decl
|inst_decl
implementation_program：
type_decl
|slover_type_decl
|pred_decl
|func_decl
|inst_decl
|mode_decl
|typesclass_decl
|instance_decl
|pragma_decl
|promise_decl
|initialise_decl
|finalise_decl
|mutable_decl
|import_module_decl
|use_module_decl
|include_module_decl
|function_fact
|pred_fact
|function_rule
|pred_rule
|user_type_defn