Maybe, I don't know. People seem to ask for this quite regularly.

Here is a slightly improved version, what do you think?

template isTemplatedType(Type...) if (Type.length == 1)

{

    mixin("alias " ~ Type[0].stringof ~ " U;");

    static if (is(Type[0] _ == U!Args, Args...))

        enum isTemplatedType = true;

    else

        enum isTemplatedType = false;

}

template TemplateArity(Type...) if (Type.length == 1 && isTemplatedType!(Type[0]))

{

    mixin("alias " ~ Type[0].stringof ~ " U;");

    static if (is(Type[0] _ == U!Args, Args...))

        enum TemplateArity = Args.length;

}

template TemplateArgs(Type...) if (Type.length == 1 && isTemplatedType!(Type[0]))

{

    mixin("alias " ~ Type[0].stringof ~ " U;");

    static if (is(Type[0] _ == U!Args, Args...))

        alias Args TemplateArgs;

}

void main()

{

    alias Tuple!(int, double) T;

    writeln(TemplateArity!T);

    writeln(TemplateArgs!T.stringof);

    writeln(isTemplatedType!T);

}