FIRST_TCL : thm_tactical list -> thm_tactical

SYNOPSIS
Applies the first theorem-tactical in a list that succeeds.

DESCRIPTION
When applied to a list of theorem-tacticals, a theorem-tactic and a theorem, FIRST_TCL returns the tactic resulting from the application of the first theorem-tactical to the theorem-tactic and theorem that succeeds. The effect is the same as: 
   FIRST_TCL [ttl1;...;ttln] = ttl1 ORELSE_TCL ... ORELSE_TCL ttln

FAILURE CONDITIONS
FIRST_TCL fails iff each tactic in the list fails when applied to the theorem-tactic and theorem. This is trivially the case if the list is empty.

SEE ALSO
EVERY_TCL, ORELSE_TCL, REPEAT_TCL, THEN_TCL.