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domain_index(+Value, -Domain, -Index)

Value is defined in Domain with positional number Index

Value: Atomic term
Domain: Variable or structure of the form Module:DomainName
Index: Variable or integer starting from 1

Description

Used to look up which domain a particular value belongs to, and which numerical index it has within this domain. Only domain definitions which are visible in the context module are taken into account.

Domain is returned as a pair DefinitionModule:DomainName which unabiguously identifies the domain definition that contains the value. Index is unified with a natural number corresponding to the position of Value within that domain definition (starting from 1).

Modes and Determinism

domain_index(+, -, -) is semidet

Modules

This predicate is sensitive to its module context (tool predicate, see @/2).

Fail Conditions

The value does not occur in any of the visible domain definitions

Exceptions

(4) instantiation fault: Value is not instantiated
(5) type error: Value is not atomic

Examples

    :- local domain(colour(red,green,blue)).

    :- export domain(vowel(a,e,i,o,u)).

    :- local domain(abc(a,b,c)).
    Domain value a not unique in module eclipse
    out of range in local domain(abc(a, b, c))
    Abort

    ?- domain_index(green, Domain, Index).
    Domain = eclipse : colour
    Index = 2
    Yes (0.00s cpu)

    ?- domain_index(a, Domain, Index).
    Domain = eclipse : vowel
    Index = 1
    Yes (0.00s cpu)

    ?- domain_index(b, Domain, Index).
    No (0.00s cpu)

    ?- domain_index(yellow, Domain, Index).
    No (0.00s cpu)