Laws for Show and Read?

[Dannyu NDos]

In the instance Show Foo, I mean "showsPrec" rather than "show".

2019년 6월 5일 (수) 16:45, Dannyu NDos <ndospark320 at gmail.com>님이 작성:

> Shouldn't it be laws that "show" must be injective and "read" must be
> surjective? Without such laws, one could define:
>
> data Foo = Foo
> instance Show Foo where
>     show _ _ = id
> instance Read Foo where
>     readPrec = pfail
>
> which should be prevented.
>
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