A series is a data structure much like a sequence, with similar kinds of operations. The difference is that in many situations, operations on series may be composed functionally and yet execute iteratively, without the need to construct intermediate series values explicitly. In this manner, series provide both the clarity of a functional programming style and the efficiency of an iterative programming style. Series is the culmination of many years of design and use of this approach, during which some 100,000 lines of application code have been written (by about half a dozen people over the course of seven years) using the series facility in nearly all iteration situations. This includes one large system (KBEmacs) of over 40,000 lines of code. In a nutshell: Think "Efficient MAPCAR". SERIES translates functional-style expressions into efficient loops.
shellsupport supports (bourne) shell scripting. It is a command line C program that provides those features that are lacking when writing portable shell scripts, because they are not covered by other portable (Posix 1003.2) tools. Amoung them are conversion routines from many ASCII date representation formats to seconds since the epoch and vice versa, file padding and wiping, symlink target display, random numbers, and counting.