"实例[安全]"在ghci":info"输出中的含义是什么？

Question

在ghci,我声明一个数据类型如下.

data Example = MakeExample deriving Show

然后,当我调用:info Example以查看派生Show实例被识别时,我得到以下输出.

> :i Example
data Example = MakeExample      -- Defined at <interactive>:17:1
instance [safe] Show Example -- Defined at <interactive>:17:37

该Show实例被认为是预期的.但是,我不明白为什么[safe]会这样.

相比之下,[safe]当我打电话不会出现:info上Bool.

> :i Bool
data Bool = False | True        -- Defined in ‘GHC.Types’
instance Bounded Bool -- Defined in ‘GHC.Enum’
instance Enum Bool -- Defined in ‘GHC.Enum’
instance Eq Bool -- Defined in ‘GHC.Classes’
instance Ord Bool -- Defined in ‘GHC.Classes’
instance Read Bool -- Defined in ‘GHC.Read’
instance Show Bool -- Defined in ‘GHC.Show’

什么是instance [safe]平均ghci的:info输出？