3.1.3 RDF literals

[det]rdf_canonical_literal(++In, -Literal)

Transform a relaxed literal specification as allowed for rdf_assert/3 into its canonical form. The following Prolog terms are translated:

Prolog Term	Datatype IRI
float	xsd:double
integer	xsd:integer
string	xsd:string
true or false	xsd:boolean
date(Y,M,D)	xsd:date
date_time(Y,M,D,HH,MM,SS)	xsd:dateTime
date_time(Y,M,D,HH,MM,SS,TZ)	xsd:dateTime
month_day(M,D)	xsd:gMonthDay
year_month(Y,M)	xsd:gYearMonth
time(HH,MM,SS)	xsd:time

For example:

?- rdf_canonical_literal(42, X).
X = 42^^'http://www.w3.org/2001/XMLSchema#integer'.

[det]rdf_lexical_form(++Literal, -Lexical:compound)

True when Lexical is the lexical form for the literal Literal. Lexical is of one of the forms below. The ntriples serialization is obtained by transforming String into a proper ntriples string using double quotes and escaping where needed and turning Type into a proper IRI reference.

• String^^Type
• String@Lang

[det]rdf_compare(-Diff, +Left, +Right)

True if the RDF terms Left and Right are ordered according to the comparison operator Diff. The ordering is defines as:

• Literal < BNode < IRI
• For literals
  • Numeric < non-numeric
  • Numeric literals are ordered by value. If both are equal, floats are ordered before integers.
  • Other data types are ordered lexicographically.

• BNodes and IRIs are ordered lexicographically.

Note that this ordering is a complete ordering of RDF terms that is consistent with the partial ordering defined by SPARQL.

Diff	is one of <, = or >