Dynamic array creation with default

[foobar]

== Quote from bearophile (bearophileHUGS at lycos.com)'s article
> foobar:
> > you raise a valid concern but this looks too complicated.
> > I'd suggest to simplify into only two cases.
> >
> > // 1) T.INIT - as you suggested the dimension should be checked
> > auto foo = new int[][](10, 20); // correct
> > auto foo1 = new int[][](10); // compilation error
> Keep in mind that currently this is correct and it generates a 1D dynamic array:
> auto v = new int[10];

Isn't this an inconsistency in the language?

// Generally speaking, allocates an instance of T on the heap
auto foo = new T;

However, "int[10]" and "new int[10]" are different types.

> > // 2) function of the array dimension
> > auto bar = new int[][](10, 20, (int x, int y) { return x*y; } );
> >
> > // if you want a default value just use:
> > auto bar1 = new int[][](10, 20, { return 3; } );
> >
> > For fixed-sized arrays the function would be CTFE-able.
> This is more complex than my suggestions :-)
> The most common case is the initialization with a constant value. I'd like this
case to be as efficient as possible, so I don't like the { return 3; }.

This syntax could be simplified if we drop "return" as suggested in another
thread. Also, couldn't we employ "lazy" for this? I don't remember how it works,
does it accept a value on the call-site?
On the other hand, I dislike the named-parameter suggestion. Named parameters
indicate in my eyes a design bug.

> The case with a more complex delegate is interesting to initialize constant arrays:
> immutable m = new int[][](10, 20, (int x, int y){ return x*y; });
> But in my opinion this is not a so common operation. And it's not able to
replace Python-style array comps:
> foo = [x ** x for x in lazyIterable]
> So I don't like your proposals.
> Maybe dsimcha will give a Phobos function to allocate & initialize a nD array
with a given const value.
> Bye,
> bearophile