\DOC FIRST_TCL

\TYPE {FIRST_TCL : (thm_tactical list -> thm_tactical)}

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

\KEYWORDS
theorem-tactical.

\DESCRIBE
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 which succeeds. The effect
is the same as:
{
   FIRST_TCL [ttl1;...;ttln] = ttl1 ORELSE_TCL ... ORELSE_TCL ttln
}
\FAILURE
{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.

\SEEALSO
EVERY_TCL, ORELSE_TCL, REPEAT_TCL, THEN_TCL.

\ENDDOC