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Module expr

Module expr 

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SPARQL expressions → SQL.

Every SPARQL value is represented by a [V]: a bundle of SQL fragments giving its kind, lexical form, datatype, language, numeric value, timestamp and boolean value. For a stored term these fragments are derived from its id (inline values decode arithmetically, hashed ones through correlated terms lookups that SQLite evaluates as early as possible). SQL NULL plays the role of the SPARQL error / unbound value; SQL three-valued logic then matches SPARQL’s error semantics for &&, || and !.