Warning: This is the manual of the legacy Guile 2.0 series. You may want to read the manual of the current stable series instead.

6.7.2.4 List Selection

These procedures are used to get some information about a list, or to retrieve one or more elements of a list.

Scheme Procedure: length lst

C Function: scm_length (lst)

Return the number of elements in list lst.

Scheme Procedure: last-pair lst

C Function: scm_last_pair (lst)

Return the last pair in lst, signalling an error if lst is circular.

Scheme Procedure: list-ref list k

C Function: scm_list_ref (list, k)

Return the kth element from list.

Scheme Procedure: list-tail lst k

Scheme Procedure: list-cdr-ref lst k

C Function: scm_list_tail (lst, k)

Return the "tail" of lst beginning with its kth element. The first element of the list is considered to be element 0.

list-tail and list-cdr-ref are identical. It may help to think of list-cdr-ref as accessing the kth cdr of the list, or returning the results of cdring k times down lst.

Scheme Procedure: list-head lst k

C Function: scm_list_head (lst, k)

Copy the first k elements from lst into a new list, and return it.