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New version of SRFI 113

This page is part of the web mail archives of SRFI 113 from before July 7th, 2015. The new archives for SRFI 113 contain all messages, not just those from before July 7th, 2015.

I have prepared a new revision of SRFI 113.  It currently resides
at <http://www.ccil.org/~cowan/temp/srfi-113.html>.  There has been a
substantial reduction in scope: the SRFI now includes only general sets,
general bags, and integer sets.  Character sets will be provided by the
existing SRFI 14 only.  Enumerations and enumeration sets will appear in
a future SRFI.  I am doing this in hopes that I will finally be able to
stop dinking with the specification and update the sample implementation
in the next pass.

I have added set-empty? and set-disjoint? predicates per Alex Shinn's

The following issues have been resolved:

12. Should we stick to just comparators, or also allow equality
predicates?  Just comparators.  For hash tables (which will be in a
future SRFI), there are backward compatibility considerations, but for
sets there are not.

13. Should we switch to six libraries (sets, bags, integer sets,
character sets, enum sets, and set-bag conversion), or stick with a single
library? (This is not about dividing the SRFI itself.)  Stick with a
single library for sets, bags, and integer sets.  Of course, enumeration
sets will be in a separate library.

14. Should we add a cursor API similar to SRFI 14's?  No.  A cursor is
only suitable for sets with a natural order of elements.

15. Should we add comparators for the various types?  No, because
unordered collections do not have any natural ordering.

Issue 8 is about enumerations and is no longer relevant to this SRFI.

The following issue is still outstanding:

16. What provisions should we have for controlling which element of a
set is preserved when a new element equal to an existing element is added?

John Cowan    cowan@xxxxxxxx    http://ccil.org/~cowan
   There was an old man                Said with a laugh, "I
     From Peru, whose lim'ricks all      Cut them in half, the pay is
       Look'd like haiku.  He              Much better for two."
                                             --Emmet O'Brien