function argument for map: why shorter form does not compile?

[Ivan Kazmenko via Digitalmars-d-learn]

Hi.

I have this reduced example:
```
import std.algorithm : map;
import std.format : format;

void main ()
{
        auto a = [1, 2, 3];
        auto b = a.map !(x => format !("%d") (x));  // ok
        auto c = a.map !(format !("%d"));  // orphan format specifier
}
```

Why the line with `b` compiles, but the line with `c` does not?
Shouldn't the compiler deduce the type for the format argument as 
a.front?

Ivan Kazmenko.