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nth1(?I, ?List, -Elem, -Rest)
Access nth element and remainder of a list
- I
- Integer position index, counting from 1
- List
- A list
- Elem
- Any term
- Rest
- A list
Description
Unifies Elem with the Nth element of List, counting from 1,
and Rest with the other elements. It can be used to select
the Nth element of List (yielding Elem and Rest), or to insert
Elem before the Nth (counting from 1) element of Rest, when it
yields List, e.g. nth1(3, List, c, [a,b,d,e]) unifies List
with [a,b,c,d,e].
Modes and Determinism
- nth1(+, +, -, -) is det
- nth1(-, +, -, -) is nondet
- nth1(-, -, -, -) is nondet
See Also
nth0 / 3, nth1 / 3, nth0 / 4