Also worth mentioning: If your list of comparisons starts growing, grep is useful.

if (grep {$a == $_} (3,77,8)) {...}      # If any of them match.
if (!grep {$a == $_} (3,77,8)) {...}     # If none of them match.
if (0 == grep {$a == $_} (3,77,8)) {...} # Same as above but more expl
+icit.
if (3 == grep {$a != $_} (3,77,8)) {...} # Also if none of them match,
+ but maybe harder to follow.
[download]

For a list of three things, it may be more cognitive load to understand. But when the list grows to five or ten things, the grep becomes more palatable.