Comment #0 by bearophile_hugs — 2010-08-17T07:22:23Z
This D2 program seems correct:
import std.algorithm: map;
void main() {
int n = 2;
map!((double x){ return x * n; })([1.0, 2.0]);
}
But DMD 2.048 prints at run time:
object.Error: Access Violation
On IRC #D jA_cOp has commented that TDPL says that the compiler should automatically choose delegate over function if it accesses its outer lexical scope.
Comment #1 by andrej.mitrovich — 2010-08-29T18:18:53Z
It does seem to be a delegate after all. If you try to evaluate it right there it shows (notice the parantheses after the lambda definition):
import std.algorithm: map;
void main()
{
int n = 2;
map!( (double x){ return x * n; }() )([1.0, 2.0]);
}
Errors:
test.d(10): Error: expected 1 function arguments, not 0
test.d(10): Error: cannot evaluate delegate double(double x)
{
return x * cast(double)n;
}
() at compile time
This seems like a compiler bug. If you use a string instead, then it will work:
import std.algorithm: map;
void main()
{
string n = "2";
map!( (string x){ return x ~ n; } )(["1.0", "2.0"]);
}
Comment #2 by eco — 2012-07-27T00:34:03Z
The code works in DMD 2.060 beta.
Comment #3 by bearophile_hugs — 2012-07-27T04:53:38Z
(In reply to comment #2)
> The code works in DMD 2.060 beta.
Right. Closed.