Class NTHCDR-TEMPLATE
Package:
COMMON-LISP.EXTENSIONS.DATA-AND-CONTROL-FLOW.UNIFICATION
Class Precedence List:
NTHCDR-TEMPLATE, ELEMENT-TEMPLATE, EXPRESSION-TEMPLATE, TEMPLATE, STANDARD-OBJECT, T.
Known Subclasses:
None.
Slots:
None.
Description:
The NTHCDR-TEMPLATE class denotes those object that are used to unify against a particular CONS of a LIST.
Template Syntax:
#T(nthcdr index item)
The NTHCDR-TEMPLATE syntax denotes the CONS item at index a LIST. A NTHCDR-TEMPLATE must be unified against a LIST object. item is unified against the element extracted from the LIST object at index by the standard function NTHCDR.
Examples:
cl-prompt> (setf e (unify '(0 1 42 3 4 5) #T(nthcdr 2 ?x))) #<ENVIRONMENT xxx> cl-prompt> (find-variable-value '?x e) (42 3 4 5) cl-prompt> (setq e (unify '(0 1 42 3 4 5) #T(nthcdr 42 ?x))) --> Error: index 42 out of bounds. FIX THIS cl-prompt> (setq e (unify #(a s d) #T(nthcdr 1 ?x))) --> Error: UNIFICATION-FAILURE
Affected By:
None.
Exceptional Situations:
Unifying an NTHCDR-TEMPLATE against a non-LIST object results in an UNIFICATION-FAILURE error being signaled.
See Also:
UNIFY
Notes:
None.