dylan-lang/opendylan — pull request #770 by waywardmonkeys (2014-06-05 09:28:24+00:00)
Title: Fix limited collection vs singleton subtype.

Given that can not be a subtype of and the only
thing defined as a possible subtype of a singleton is another
identical singleton, it makes sense to have this also result
in a result of ``#f``.

This fixes this runtime warning:

Warning: Method specificity of unorderable methods
{:
{: ??? (<&type>, <&singleton>)},
{: ??? (<&limited-collection-type>, <&type>)}}
applying
{: ^subtype?}
to
{: {<&limited-sequence-type>}, {<&singleton>}}
was determined with arbitrary and capricious rules.