An output range for E won't be automatically an output range for [E]
anymore. The same, an output range for [E] won't be automatically an
output range for E. Automatic E <-> [E] conversion seems to be a nice
feature at first glance, but it causes much ambiguity.
1) If I want that my output range accepts only UTF-8 strings but not
single characters (because it could be only part of a code point and
look like broken UTF-8 without the remaining code units), I can't do it
because an OutputRange(R, E) can't distinguish between char and string.
2) Here is an example from 2013:
import std.range;
import std.stdio;
Appender!(const(char)[][]) app;
put(app, "aasdf");
put(app, 'b');
writeln(app.data);
This outputs: ["aasdf", "\0"].
Whether it is a common case or not, such code just shouldn't compile.
Eugen Wissner
0c8f1eb4ce