0 past simple and past participle of trail --
1 to (allow something to) move slowly along the ground or through the air or water, after someone or something: --
2 to be losing to your competitor in a competition: --
3 to follow the trail of someone or something --
Indeed, if such a variable would be chain trailed instead of value trailed, only one instead of two slots would be used on the stack.
This reduces the chance that the binding needs to be trailed.
Thus, we will need a different variant for each possible combination of variables that do and do not need to be trailed.
So in the post-description we move all deep trailed arguments to the set of shallow trailed variables, together with all variables they share with.
These are the only ones that can contain entries which have not been trailed.
As only their associated cells need to be trailed, we will refer to this kind of trailing as shallow trailing.
Thus, we can only reconstruct the chain if all cells in the chain are trailed.
Thus, after the unification both variables will be shallow trailed.
