[Haskell-cafe] Hyrum's law (Was: [RFC] Support Unicode characters in instance Show String)

Henning Thielemann lemming at henning-thielemann.de
Thu Jul 8 17:20:00 UTC 2021

moving to Haskell Cafe

On Thu, 8 Jul 2021, Bardur Arantsson wrote:

> On 08/07/2021 17.53, Oleg Grenrus wrote:
> [--snip--]
>> 78 out of 2819 tests failed (35.88s)
> The use of Show in 'golden' test suites is interesting because Show
> doesn't really guarantee any real form of stability in its output.
> I guess Hyrum's Law applies here too.
> Anyway... just an idle observation. Obviously, breaking loads of test
> suites is going to be hard to swallow.

I found this explanation:

Nice to have a name for this observation.

I think the problem can be relaxed if there are multiple implementations 
for the same interface. But then you often find, that the implementations 
do not even adhere to the interface, thus people start guessing what the 
interface actually means.

I hope that in the future we can describe interfaces more formally, such 
that a user knows what he can rely on.

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