VALID
Tactical.VALID : tactic -> tactic
Makes a tactic fail if it would otherwise return an invalid proof.
If tac
applied to the goal (asl,g)
produces
a justification that does not create a theorem A |- g
, with
A
a subset of asl
, then
VALID tac (asl,g)
fails (raises an exception). If
tac
produces a valid proof on the goal, then the behaviour
of VALID tac (asl,g)
is the same as
tac (asl,g)
Fails by design if tac
produces an invalid proof when
applied to a goal. Also fails if tac
fails when applied to
the given goal.