HEADGOALTactical.HEADGOAL : tactic -> list_tactic
The list-tactic which applies a tactic to the first member of a list of goals.
If tac is a tactic, HEADGOAL tac is a
list-tactic which applies the tactic tac to the first
member of a list of goals.
The application of HEADGOAL to a tactic never fails. The
resulting list-tactic fails the goal list is empty or or finally if
tac fails when applied to the first member of the goal
list.
Applying a tactic to the first subgoal.
Where tac1 and tac2 are tactics,
tac1 THEN_LT HEADGOAL tac2 applies tac1 to a
goal, and then applies tac2 to the first resulting
subgoal.
Tactical.THEN_LT, Tactical.NTH_GOAL, Tactical.THEN1, Tactical.LASTGOAL