RDF.Literal.plain-question-mark

You're seeing just the function plain-question-mark, go back to RDF.Literal module for more information.

Specs

plain?(t()) :: boolean()

Returns if a literal is a plain literal.

A plain literal may have a language, but may not have a datatype. For all practical purposes, this includes xsd:string literals too.

see http://www.w3.org/TR/rdf-concepts/#dfn-plain-literal