Template matching and is expression

[Piotr Szturmaj]

Hello,

I'm using D2.051 and following code:

import std.variant;

template Nullable(T)
{
     alias Algebraic!(T, void*) Nullable;
}

template isNullable(T)
{
     static if (is(T X == Nullable!U, U))
         enum isNullable = true;
     else
         enum isNullable = false;
}

static assert(isNullable!(Nullable!int));

and above static assert fails. Neither this works:

template isNullable(T : Nullable!U, U)
{
     enum isNullable = true;
}

template isNullable(T)
{
     enum isNullable = false;
}

static assert(isNullable!(Nullable!int));

Question is, what I'm doing wrong?