Better idea for double list comprehension?

[CJS]

>
> to!string(c)   ===>   c.text
>

That's more concise but I also think it's more confusing. I 
assume that to!string is doing the exact same thing, but I was 
hoping for something to do the appropriate implicit 
conversations. Especially to a range of length 1, though I can 
understand that kind of auto-magical conversion would be annoying 
in a number of important instances.

I changed the code to this:



import std.stdio : writeln;
import std.range : chunks, chain;
import std.algorithm;
import std.array;
import std.conv;

auto cross(R1, R2)(R1 A, R2 B) {
     return cartesianProduct(A, B).map!(ab => ab[].text).array;
}


void main(){
     const string letters = "ABCDEFGHI";
     const string digits = "123456789";

     auto cols = digits;
     auto rows = letters;

     auto squares = cross(rows, cols);
     string[][] unitlist;
     foreach(c; cols){
         unitlist ~= cross(rows, to!string(c));
     }
     foreach(r; rows){
         unitlist ~= cross(to!string(r), cols);
     }
     foreach(r; chunks(rows, 3)){
         foreach(c; chunks(cols, 3)){
             unitlist ~= cross(to!string(r),to!string(c));
         }
     }

     string[][][string] units;
     string[][string] peers;

     foreach(s; squares){
         units[s] = unitlist.filter!(x => any!(y => s==y)); \\line 
37
     }

     foreach(s; squares){
         peers[s] = remove(chain(units[s]), s); \\line 41
     }

}


On dmd 2.064.2 (downloaded and installed today) on 64-bit linux I 
get the following errors:

sudoku.d(37): Error: cannot resolve type for any!((y) => s == y)
/home/cjordan1/dmd2/linux/bin64/../../src/phobos/std/algorithm.d(1381): 
Error: template instance sudoku.main.__lambda1!(string[]) error 
instantiating
/home/cjordan1/dmd2/linux/bin64/../../src/phobos/std/algorithm.d(1369): 
        instantiated from here: FilterResult!(__lambda1, 
string[][])
sudoku.d(37):        instantiated from here: filter!(string[][])
/home/cjordan1/dmd2/linux/bin64/../../src/phobos/std/algorithm.d(1369): 
Error: template instance sudoku.main.FilterResult!(__lambda1, 
string[][]) error instantiating
sudoku.d(37):        instantiated from here: filter!(string[][])
sudoku.d(37): Error: template instance sudoku.main.filter!((x) => 
any!((y) => s == y)).filter!(string[][]) error instantiating
sudoku.d(41): Error: cannot implicitly convert expression 
(remove(chain(units[s]), s)) of type string[][] to string[]

  Lines 37 and 41 are noted in the above code.