Sum of Number List, with capable of nesting in AppleScript

sum.scpt

on run
	sum({1, 2, 3, {1, 2}})
end run

on sum(arg)
	-- 数値リストの総和を求める
	-- リストが含まれている場合は再帰的に中身も合計する
	if arg is equal to {} then
		set result to 0
	else if class of arg's first item is equal to list then
		-- 先頭の要素がリストなら、そちらにもsumを適用
		set result to sum(arg's first item) + sum(arg's rest)
	else
		try
			set result to (arg's first item as number) + sum(arg's rest)
		on error
			--数値に変換できない要素は無視
			set result to sum(arg's rest)
		end try
	end if
end sum