( condition ) [ ( true statements  ) ] ifTrue
( condition ) [ ( false statements ) ] ifFalse
( condition ) [ ( true statements  ) ] [ ( false statements ) ] if

: foo ( n- )
  [ 1 = ] [ drop ( if quote evaluates to true ) ] when
  [ 2 = ] [ drop ( if quote evaluates to true ) ] when
  [ 3 = ] [ drop ( if quote evaluates to true ) ] when
  drop ( default action ) ;
