-1, per the very confusing errors that would ensue.

If this behavior is desired, you can use a newtype wrapper. As it happens, this fits the pattern of ANum. (Any Applicative can be made an instance of Num in this way.)

-- Dan Burton

On Sun, Nov 11, 2018 at 12:28 AM Tom Murphy <amindfv@gmail.com> wrote:

On 11/11/18, Henning Thielemann <lemming@henning-thielemann.de> wrote:
>
> On Sun, 11 Nov 2018, Henning Thielemann wrote:
>
>> On Sat, 10 Nov 2018, Daniel Cartwright wrote:
>>
>>> relevant reddit comment
>>> thread:https://www.reddit.com/r/haskell/comments/9vtis5/the_universe_of_discourse_i_hate_the_environment/e9f1lea?utm_so
>>> urce=reddit-android
>>
>> https://wiki.haskell.org/index.php?title=Num_instance_for_functions&oldid=36632
>>
>> In short: It would make 2(x+y) no longer a type error but equivalent to 2.
>> We
>> would lose a lot of type safety for little syntactic gain.
>
> Btw. before adding more Wat instances please implement the GHC warning
> about such instances:
>     https://ghc.haskell.org/trac/ghc/ticket/11796

This is my feeling as well.

Tom
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