— Scheme Procedure: length+ clist

Return the length of the argument list lst. When lst is a circular list, #f is returned.

— Scheme Procedure: concatenate l-o-l
— Scheme Procedure: concatenate! l-o-l

Construct a list by appending all lists in list-of-lists.

concatenate! may modify the structure of the given lists in order to produce the result.

— Scheme Procedure: append-reverse rev-head tail
— Scheme Procedure: append-reverse! rev-head tail

Reverse rev-head, append tail and return the result. This is equivalent to (append (reverse rev-head) tail), but more efficient.

append-reverse! may modify rev-head in order to produce the result.

— Scheme Procedure: zip clist1 [rest...]

Return a list as long as the shortest of the argument lists, where each element is a list. The first list contains the first elements of the argument lists, the second list contains the second elements, and so on.

— Scheme Procedure: unzip1 lst
— Scheme Procedure: unzip2 lst
— Scheme Procedure: unzip3 lst
— Scheme Procedure: unzip4 lst
— Scheme Procedure: unzip5 lst

unzip1 takes a list of lists, and returns a list containing the first elements of each list, unzip2 returns two lists, the first containing the first elements of each lists and the second containing the second elements of each lists, and so on.