为什么 "not nil" return 在 Lua 中为真？
Why does "not nil" return true in Lua?
出于好奇，我已经使用 repl.it 来查看它返回的内容，结果是
not nil
返回 true
这是为什么？是不是因为 Lua 一切最终都应该是真或假？
Repl.it link: https://repl.it/repls/SanePastelHarrier
因为nil转换为布尔值时是false：
2.2 Booleans
The boolean type has two values, false and true, which represent the traditional boolean values. However, booleans do not
hold a monopoly of condition values: in Lua, any value may represent a
condition. Conditionals (such as the ones in control structures)
consider both false and nil as false and anything else as true.
Beware that, unlike some other scripting languages, Lua considers both zero
and the empty string as true in conditional tests.
并且 not 将其参数视为布尔值：
3.3 Logical Operators
The logical operators areand, or, and not. Like control structures, all logical operators consider both false and nil
as false, and anything else as true.
出于好奇，我已经使用 repl.it 来查看它返回的内容，结果是
not nil
返回 true
这是为什么？是不是因为 Lua 一切最终都应该是真或假？
Repl.it link: https://repl.it/repls/SanePastelHarrier
因为nil转换为布尔值时是false：
2.2 Booleans
The boolean type has two values,
falseandtrue, which represent the traditional boolean values. However, booleans do not hold a monopoly of condition values: in Lua, any value may represent a condition. Conditionals (such as the ones in control structures) consider bothfalseandnilasfalseand anything else astrue. Beware that, unlike some other scripting languages, Lua considers both zero and the empty string astruein conditional tests.
并且 not 将其参数视为布尔值：
3.3 Logical Operators
The logical operators are
and,or, andnot. Like control structures, all logical operators consider bothfalseandnilasfalse, and anything else astrue.