Provides list-processing utilities inspired by the 'SRFI-1' list library for Scheme (< https://srfi.schemers.org/srfi-1/srfi-1.html>), including car/cdr family accessors, zip, pairwise, for.each, pair.fold.right and friends. Higher-order helpers that are orthogonal to list processing are deferred to the 'functional' package; this package is freely a mixture of implementation and API.