In a naive implementation of a Sequence adapter, adapting a
non-self-destructive (multi-pass) Sequence having a reference-semantics
Generator produces a self-destructive adapted view. This is technically
correct because Sequences are allowed to be self-destructive, and
theoretically every multi-pass Sequence would be a Collection. However
Sequences are much easier to build than Collections, so users are likely
to make them, and it would be extremely surprising if adapting a
self-preserving Sequence yielded a self-destructive one.
Swift SVN r18350
As declared, Dictionary's keys and values were private. Instead of
hiding Map away as _Map, give it a "nice" verbose name and expose it
through a "nice" lowercase global function called map(), which we
overload so it works on both Collections and Sequences, returning a
Collection when that's what it started on.
We'll follow this pattern for filter, which was requested on Array. The
implementation is easy once you have a lazy view!
Swift SVN r18340
The name may have the wrong implication to a C++'er, but the point is
that this Collection is a Lazy version of the map() function. Maybe we
should be giving our Collections capitalized lazy versions of their
member algorithms, e.g.
a.Map {something}
Swift SVN r16110
