Rules for class methods and Safe Haskell

Wolfgang Jeltsch g9ks157k at
Thu Nov 13 19:03:39 UTC 2014

Am Freitag, den 15.08.2014, 23:10 +0300 schrieb Wolfgang Jeltsch:
> Hi,
> the module Control.Arrow declares a set of rules for the Arrow class. It
> is marked “Trustworthy”, probably to allow these rules to actually fire.
> Now these rules are only correct for class instances that actually
> satisfy the arrow laws. If the author of another module defines an
> instance of Arrow that does not respect the laws, this other module
> could still be considered “Safe” by GHC, although the rules from
> Control.Arrow are bogus now.
> Is this considered a problem?
> All the best,
> Wolfgang


could someone please answer this e-mail? This issue is important for me.

All the best,

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