Solves a goal which is an instance of the supplied theorem.
DESCRIBE
When given a theorem A' |- t and a goal A ?- t' where t can be matched
to t' by instantiating variables which are either free or
universally quantified at the outer level, including appropriate type
instantiation, MATCH_ACCEPT_TAC completely solves the goal.
A ?- t'
========= MATCH_ACCEPT_TAC (A' |- t)
Unless A' is a subset of A, this is an invalid tactic.
FAILURE
Fails unless the theorem has a conclusion which is instantiable to match that
of the goal.
EXAMPLE
The following example shows variable and type instantiation at work. We can use
the polymorphic list theorem HD: