| relates a term and one of its arguments.
arg(+N, +CompoundTerm, -Argument)
arg/3 unifies Argument with the N-th argument
of CompoundTerm.
Arguments
N integer (between 1 and the arity of CompoundTerm)
CompoundTerm compound term
Argument term
Examples
| arg(1, f(a,b,c), X). |
Succeeds with substitution X <- a. |
| arg(2, f(X, g((a,h(a,b))), g(a,Z)). |
Succeeds with substitution Z <- h(a,b) |
| arg(3,f(a,b),X). |
Fails. |
Standard
This predicate is part of the ISO-Prolog Standard.
See also
copy_term/2,
functor/3,
'=..'/2.
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