
HANDBOOK
/ GENTLE PRIMER
/ A Summary of Predefined Predicates
/
The Predicate where
The predicate where is defined for each type.
It simply copies its input parameter to its output parameter.
Hence, it may be used to construct a value and assign it to a variable
as in
where(list(red, nil) -> L)
or to inspect a value and define variables with subterms as in
where(L -> list(Head, Tail))
This predicate is of particular use in alternative statements
and is discussed in the corresponding section.
