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Pack format_spec -- prolog/format_spec.pl
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 format_error(+Goal, -Error:string) is nondet
True if Goal exhibits an Error in its format string. The Error string describes what is wrong with Goal. Iterates each error on backtracking.

Goal may be one of the following predicates:

DCG for parsing format strings. It doesn't yet generate format strings from a spec. See format_spec/2 for details.
 format_spec(+Format, -Spec:list) is semidet
Parse a format string. Each element of Spec is one of the following:
  • text(Text) - text sent to the output as is
  • escape(Num,Colon,Action) - a format escape

Num represents the optional numeric portion of an esape. Colon represents the optional colon in an escape. Action is an atom representing the action to be take by this escape.

 spec_arity(+FormatSpec, -Arity:positive_integer) is det
True if FormatSpec requires format/2 to have Arity arguments.
 spec_types(+FormatSpec, -Types:list(type)) is det
True if FormatSpec requires format/2 to have arguments of Types. Each value of Types is a type as described by error:has_type/2. This notion of types is compatible with library(mavis).