> Is there a ticket?
#10982
Janek
---
Politechnika Łódzka
Lodz University of Technology
Treść tej wiadomości zawiera informacje przeznaczone tylko dla adresata.
Jeżeli nie jesteście Państwo jej adresatem, bądź otrzymaliście ją przez pomyłkę
prosimy o powiadomienie o tym nadawcy oraz trwałe jej
I agree too.
Is there a ticket? Does it emit a warning right now?
Simon
From: ghc-devs [mailto:ghc-devs-boun...@haskell.org] On Behalf Of Richard
Eisenberg
Sent: 11 December 2015 16:02
To: Michael Sloan <mgsl...@gmail.com>
Cc: ghc-devs@haskell.org
Subject: Re: Unused type variables wi
I agree with Michael. This should not emit a warning.
While you're in this area, make sure that
> type instance F _ _ = Int
indeed matches `F Char Bool`. It's easy to imagine both underscores being
treated as the same variable, which is not what the user intends.
Thanks,
Richard
On Dec 10,
I definitely think this should be considered a usage. Ideally, you should
always be able to resolve warnings, but there'd be no straightforward way
to do so if LHS-only usages cause warnings. Also, It's quite useful to use
type variables only on the LHS. Usage example:
An intersting thing came up when implementing warnings for unused type
variables in type family
patterns (#10982 / D1576):
type family X a b where
X a a = Int
Should we emit a warning that `a` is unused? It does not appear in the RHS but
it is actually used
because of non-linear pattern.
