Comment #0 by andrej.mitrovich — 2010-09-03T10:05:39Z
From: http://www.digitalmars.com/d/2.0/phobos/std_range.html#Sequence
// a[0] = 1, a[1] = 2, a[n] = a[0] + n * a[1]
auto odds = sequence!("a[0] + n * a[1]")(1, 2);
This has been reported in bug 3181 for not compiling.
But there's a workaround. If I use the "a.field[]" syntax instead of "a[0]", then the original example in the documentation works:
auto odds = sequence!("a.field[0] + n * a.field[1]")(1, 2);
There are also some weird bugs in the sequence unittest in range.d. Apparently you can't call both Sequence and sequence in the same code. That code is commented out with "@@BUG", but there's no bug number so I guess it wasn't reported yet, or maybe someone is already working on it..
But anyway, here's the gist of it:
import std.range;
import std.typecons;
void main()
{
alias Sequence!("a.field[0] + n * a.field[1]", Tuple!(int, int)) Gen;
auto y = sequence!("a.field[0] + n * a.field[1]")(0, 4);
}
C:\DMD\dmd2\windows\bin\..\..\src\phobos\std\range.d(2459): Error
: this for _cache needs to be type Sequence not type Sequence!("a
.field[0] + n * a.field[1]",Tuple!(int,int))
If you uncomment either line, the example compiles.
Comment #1 by andrej.mitrovich — 2011-03-09T11:48:37Z
Both of these have been fixed in a recent release.