First of all, this code:

import std.stdio;

template check( char ch1, char ch2)
{
	const bool check = ch1 == ch2;
}

void main()
{
	const char[] s = "123+456" ;
	writefln( check!( '+', s[3] ));
}

gives the following message:  "s is used as a type"

Can somebody explain to me what's wrong with the code?

But if I add two characters (check the differences :-) ):

import std.stdio;

template check( char ch1, char ch2)
{
	const bool check = ch1 == ch2;
}

void main()
{
	const char[] s = "123+456" ;
	writefln( check!( '+', (s)[3] ));   // added parentheses
}

it compiles fine?

roel