Performing a test for callable that is minimally module aware and Should be deprecated and there should be two new predicates, one Module-qualification of meta-argument (see meta_predicate/1) Terms suchĪs (22,true) are considered callable, but cause call/1 Note that callable only tests the surface term. Intended as a type-test for arguments to call/1, call/2Įtc. callable( True if Term is bound to an atom or a compound term. See also functor/3Īnd compound_name_arguments/3. compound( True if Term is bound to a compound term. In addition, the symbol (empty list) is atomic, but notĪn atom. SWI-Prolog defines the following atomic datatypes: atom ( atom/1), atomic( True if Term is bound (i.e., not a variable) and is notĬompound. Traditional Prolog systems, double quoted text is often mapped to a list Text between double quotes, such as 'hello'.

Starting with version 7, the syntax for a string object is Refers to the built-in atomic type string as described in sectionĥ.2. string( True if Term is bound to a string. blob( True if Term is a blob of type Type. number( True if Term is bound to a rational number (including Integer and there are no common divisors between NumeratorĪnd Denominator. The Numerator and DenominatorĪre in canonical form, which means Denominator is a positive

rational( -Denominator) True if Term is a rational number with given Numeratorĭenominator. rational( True if Term is bound to a rational number. float( True if Term is bound to a floating point number. integer( True if Term is bound to an integer. nonvar( True if Term currently is not a free variable. var( True if Term currently is a free variable. Type-test predicates have noĮrror condition and do not instantiate their argument. Type tests are semi-deterministic predicates that succeed if theĪrgument satisfies the requested type.

Swi prolog org