Yet another chainsaw massacre.
One of the most obnoxious annoyances with C++ metaprogramming
is the need to insert `typename` and `template` qualifiers into
most definitions, to help the compiler to cope with the syntax,
which is not context-free.
The recent standards adds several clarifications, so that most
of these qualifiers are redundant now, at least at places where
it is unambiguously clear that only a type can be given.
GCC already supports most of these relaxing rules
(Clang unfortunately lags way behind with support of newer language features...)
As follow-up from the preceding refactorings,
it is now possible to drastically simplify several type signatures.
Generally speaking, iterator pipelines can now pass-through the result type,
and thus it is no longer necessary to handle this result type explicitly
In the case of `IterStateWrapper`, the result type parameter was retained,
but moved to the second position and defaulted; sometimes it can be relevant
to force a specific type; this is especially useful when defining an
`iterator` and a `const_iterator` based on the same »state-core«
* Lumiera source code always was copyrighted by individual contributors
* there is no entity "Lumiera.org" which holds any copyrights
* Lumiera source code is provided under the GPL Version 2+
== Explanations ==
Lumiera as a whole is distributed under Copyleft, GNU General Public License Version 2 or above.
For this to become legally effective, the ''File COPYING in the root directory is sufficient.''
The licensing header in each file is not strictly necessary, yet considered good practice;
attaching a licence notice increases the likeliness that this information is retained
in case someone extracts individual code files. However, it is not by the presence of some
text, that legally binding licensing terms become effective; rather the fact matters that a
given piece of code was provably copyrighted and published under a license. Even reformatting
the code, renaming some variables or deleting parts of the code will not alter this legal
situation, but rather creates a derivative work, which is likewise covered by the GPL!
The most relevant information in the file header is the notice regarding the
time of the first individual copyright claim. By virtue of this initial copyright,
the first author is entitled to choose the terms of licensing. All further
modifications are permitted and covered by the License. The specific wording
or format of the copyright header is not legally relevant, as long as the
intention to publish under the GPL remains clear. The extended wording was
based on a recommendation by the FSF. It can be shortened, because the full terms
of the license are provided alongside the distribution, in the file COPYING.
Originally, this helper was called `IterIndex`, thereby following a
common naming scheme of iteration-related facilities in Lumiera, e.g.
* `IterAdapter`
* `IterExplorer`
* `IterSource`
However, I myself was not able to recall this name, and found myself
now for the second time unable to find this piece of code, even while
still able to recall vaguely that I had written something of this kind.
(and unable to find it by a text search for "index", for obvious reasons)
So, on a second thought, the original name is confusing: we do not create
an index of / for iterators; rather we are iterating an index. So this
is what it should be called...
