EXEC ( 'SPARQL ||
		' CREATE SPIN LIBRARY <{library-IRI}> 
			  { 
			     CLASS {<iri-of-class-to-which-rule-is-scoped>} 
			              { 
						      RULE <{rule-iri}> 
				                   { 
							         CONSTRUCT { 
									 			 ?this <{magic-predicate-iri}> ?area 
												} 
				                     WHERE { 
				                             { Query-Body } 
				                           } 
   
				                     UNION STORAGE 
				                  } 
			   			} 
				} 
		   ASK WHERE { <nosuch> <nosuch> <nosuch> }'
    ) ;
  
-- Note: 
-- UNION STORAGE clause ensures fusion of calcuated and existing values when inferring objects of the 
-- <http://example.org/shapes#area> relation identified by the variable ?area. Thus, if excluded inferred 
--  objects of the <http://example.org/shapes#area> relation would only comprise calculated values.

-- Note:
-- The query at the end is validation one, it's purpose is to flag the presence of failed preconditions if it's ASK or return the 
-- list of failed preconditions if it's a SELECT.
-- The query with CREATE MACRO LIBRARY/CREATE SPIN LIBRARY is compiled into call of function DB.DBA.RDF_SML_CREATE(). The function -- can be redefined if one want to shoot his leg in an unusual way, but its default version is pretty short. First it is making a 
-- "dry run" of the whole statement without creating or storing the library and executes the query at its end (e.g.,, this ASK WHERE -- { <nosuch> <nosuch><nosuch>}. If the query at the end signals an error then the error is resignalled and the library is not 
-- created. if the query returns any non-empty result-set then an "Assertion failed: the validation query of macro library should 
-- return nothing" error is signalled. If no data rows returned by the query, the DB.DBA.RDF_SML_CREATE() alters the system metadata --  to store the library.

-- Usage
-- Pragma

DEFINE input:macro-lib <{library-IRI}>  ;

-- Storage Attachment 
SPARQL ALTER QUAD STORAGE <{storage-iri}> { ATTACH MACRO LIBRARY <{library-IRI}> };