This page is part of the web mail archives of SRFI 1 from before July 7th, 2015. The new archives for SRFI 1 contain all messages, not just those from before July 7th, 2015.
in Issues, Olin noted: > 3.When do n-ary mapping functions (MAP, MAP!, FOR-EACH, PAIR-FOR-EACH, > APPEND-MAP, APPEND-MAP!, FILTER-MAP, MAP-IN-ORDER) terminate? > 1.When any list runs out? > 2.When the first list runs out? > 3.All lists must be of equal length? > My preferences are in the order listed. R4RS says #3. Hence this spec > requires #1. Any changes to this *must* happen by the end of the SRFI > discussion period. Dylan, which has a fairly general collections mechanism, also takes approach #1. Generalizing lists, a collection in Dylan is regarded as a mapping from keys to values. The keys for lists and vectors are integers starting at zero. n-ary mapping functions do an intersection-join on the keys of their arguments, and hence, for the list case, only operate on the common keys, ie, along the shortest list. -- Donovan Kolbly ( RScheme Development Group ( d.kolbly@xxxxxxxxxxx ( http://www.rscheme.org/~donovan/