 {T}

where B(i) == f(g(i)) <span class="kw">if</span> g(i) != -<span class="num">1</span>
           == NA      <span class="kw">if</span> g(i) == -<span class="num">1</span></pre><p>For this to work, the maximum value M in the co-domain of g must be &lt;= A.length.
We also augment the mapping f to send -1 to the corresponding NA value of type T.</p><p>For example, suppose we have Index(0,1,2,4) and Index(0,1,2,3). Performing
a full outer join would yield the following ReIndexer:</p><ul><li>lTake = {0, 1, 