Re: suppress warning "Defined but not used: type variable ‘x’" in GHC-8.0

Carter Schonwald carter.schonwald at
Sat Jan 9 23:06:07 UTC 2016

Have you tried _x instead?

On Saturday, January 9, 2016, Henning Thielemann <
lemming at> wrote:

> GHC-8.0 emits several new warnings of this kind:
>    Defined but not used: type variable ‘x’
> for declarations like
>    type instance Snd x y = y
> Enthusiastically, I started to replace unused type function arguments by
> underscores, only to find out that older GHC versions do not accept that.
> With what option can I disable this warning? Or can it be removed from
> -Wall for now?
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