# Using RDF literals
RDF literals are currently represented in one of the three formats below. Note that RDF 1.1
no longer has plain literals. Plain literals are expected to be dropped.
- literal(type(Type, Atom))
- literal(lang(Lang, Atom)).
Also note that literals are expressed in their _lexical form_. This means that the RDF
literal value `42` is `literal(type('http://www.w3.org/2001/XMLSchema#integer', '42'))`.
This is not very practical. Future versions are likely to change this. We consider the
model below, following the _Turtle_ conventions. In this case, `Value` will be a suitable
Prolog representation for known values types.
In addition to a simple direct match to a literal, rdf/3 and rdf/4 accept a query specification
like below. See rdf/3 for all possible specifications. The _prefix_, _ge_ and _between_ searches exploit the fact that all literals are stored in a binary tree.
rdf(S, P, literal(prefix('Jan'), Value)).
## Full text search
The library(semweb/rdf_litindex) indexes _tokens_ inside literal values. The primary predicate is rdf_find_literal/2. The following example finds all literals that contain a token that has the same stem as `exploit`.
## Matching languages
The predicate lang_matches/2 is provided to match a language pattern against a concrete language. For example: