This module allows you to write programs that can be executed on a triplestore or directly on the in-memory SWI-Prolog rdf database.

Sparqlprog defines predicates such as rdf_path/3 and str_starts/2. These are usually compiled down to SPARQL queries. This module provides prolog implementations for these predicates using predicates such as rdf/3

Many of the predicates here take an argument strlike - this can be either an atom or a string.

 lcase(+S:strlike, ?V:str)

 regex(?String, +Pattern, +Flag) is nondet

 regex(?String, +Pattern) is nondet

equivalent to REGEX in SPARQL

corresponds to re_match/2 in SPARQL

 eval_to_atom(?X, ?A) is nondet

evaluates expression X ensuring A is an atom

 str_starts(+S:strlike, +Sub:strlike) is semidet

 str_ends(+S:strlike, +Sub:strlike) is semidet

 str_before(+S:strlike, +Sep:strlike, ?Sub:strlike) is det

 str_after(+S:strlike, +Sep:strlike, ?Sub:strlike) is det

 str_replace(+S:strlike, +Match:strlike, +Replace:strlike, ?NewStr:strlike) is det

 concat(?S1, ?S2, ?S) is nondet

equivalent to CONCAT in SPARQL

 concat(+S1, +S2, +S3, ?S) is nondet

equivalent to CONCAT in SPARQL

 count(?L, ?N) is nondet

 agg_max(?L, ?N) is nondet

 group_concat(?L, ?Sep, ?V) is nondet

 aggregate_group(+AggExpression, +GroupBys:list, +Goal, ?Val) is det

perform an aggregate query

equivalent to GROUP BY queries in SPARQL

maps to aggregate/3 in prolog

 rdf_path(?S, +Path, ?O, ?G) is nondet

 rdf_path(?S, +Path, ?O) is nondet

Evaluate an rdf path expression in terms of rdf/3.

See https://www.w3.org/TR/sparql11-query/#propertypaths

== Path = Pred OR \Path OR P|Q OR P\Q OR zeroOrMore(Path) OR oneOrMore(Path) OR inverseOf(Path) ==

 optional(?G) is det

call G once, succeed if G fails

equivalent to OPTIONAL in SPARQL

 ensure_atom(?Str:strlike, ?Atom:atom) is det

convert a string, literal, or any strlike entity to an atom

 ensure_string(?A, ?Str:string) is det

convert an entity to its string representation

 ensure_atoms(?Input:list, ?Atoms:list) is det

 if(?E1, ?E2, ?E3, ?R) is nondet

 bind(?ReturnValue, +FunctionTerm)

evaluates a function term. The function term can be a:

• SPARQL builtin (e.g. coalesce, regex)
• An arithmetic term (e.g. 1 + (2 / X) )
• An abritrary prolog goal term in which:
  • the final argument N is treated as result/output
  • the arguments 1..( N-1) are treated as inputs
  • inputs should be ground
  • determinism or semi-determinism assumed when inputs are ground

 seval(+FunctionTerm, ?ReturnValue)

evaluates a function term

this is the same as bind/2 with args reversed.

Undocumented predicates

The following predicates are exported, but not or incorrectly documented.

 regex(Arg1, Arg2)

 iri_prefix_curie(Arg1, Arg2, Arg3)

 iri_prefix(Arg1, Arg2)

 iri_curie(Arg1, Arg2)

 curie_prefix(Arg1, Arg2)

 rdf_path(Arg1, Arg2, Arg3)