On 7/10/12 9:56 AM, Jacob Carlborg wrote:
On 2012-07-10 15:28, Andrei Alexandrescu wrote:
We can arrange things in the library that a custom message is issued, or
in the compiler to do it once for all. At any rate whenever there's an
error pointing somewhere in the library's code that's an insufficient
template constraint that should be fixed.
I mean, is it possible to have the original code work?
auto bar = foo.chain("bar");
Or perhaps more appropriate:
auto bar = foo.append("bar");
It would be possible to chain a single element to the end of a range.
One related thing to do is to define singletonRange(x) that returns a
range with exactly one element, namely x.
I understand. So you need to use array() to convert the lazy map result
into an eager array. I disagree this is unintuitive, if it were then
very little of D would make sense are lazy, non-array ranges are
everywhere.
Tell me what is the point of std.algorithm and ranges if I have to
convert every single result of an algorithm to an array before I can use
it with an other algorithm? I thought the whole idea was to avoid
allocations between different usages of algorithms.
Ranges and std.algorithm obey simple, mathematical realities deriving
from algorithm and storage topology constraints. For example sort works
in place so it generally can't work on mapped stuff because there's no
place to put the sorted contents. Also sort needs a random-access range
to work with so it can't work e.g. with the result of filter, which
necessarily yields a non-random-access range. And so on.
Now I understand if you come from a place where there's no concern over
hidden allocations and extra work for the benefit of convenience, you
may find std.algorithm less easy to work with. But drawing the
conclusion that std.algorithm is badly designed or gratuitously
difficult to use would be a mistake. I opine I can recognize a good vs.
bad design even when it's mine, and in my opinion std.algorithm is a
good design and that most of your opposing impressions derive from a
misunderstanding of its charter.
Andrei
