Check template parameter whether it has "length"

[tcak via Digitalmars-d-learn]

I am "trying" to write a function that takes an array of items, 
and returns the length of longest item.

[code]
size_t maxLength(A)( const A[] listOfString ) if( __traits( 
hasMember, A, "length" ) )
{
        return 0; // not implemented yet
}
[/code]
I tried it with

if( __traits( compiles, A.length ) )

as well. But compiler doesn't match it.

writeln("Max Length: ", maxLength( ["foo", "123456789"] ));

Compilers says it cannot deduce function from argument types ...

I do not want to check whether the type "A" is string, char[], 
etc. As long as it has length (please do not put me into ranges, 
library functions etc as much as possible), I want the function 
to accept it.