HEADGOAL : tactic -> list_tactic
STRUCTURE
SYNOPSIS
The list-tactic which applies a tactic to the first member of a list of goals.
DESCRIPTION
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.
FAILURE
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.
USES
Applying a tactic to the first subgoal.
EXAMPLE
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.
SEEALSO
HOL  Kananaskis-14