<div dir="auto">How do you deprecate an instance?</div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Sun, Nov 24, 2019, 12:18 PM Dan Burton <<a href="mailto:danburton.email@gmail.com">danburton.email@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div>If someone depends on this behavior, we should give them the courtesy of a proper deprecation cycle to aid them in fixing their code. That's what a deprecation cycle is for. Don't skip it.<br><div><br clear="all"><div><div dir="ltr" data-smartmail="gmail_signature">-- Dan Burton</div></div><br></div></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Sun, Nov 24, 2019 at 7:57 AM Oleg Grenrus <<a href="mailto:oleg.grenrus@iki.fi" target="_blank" rel="noreferrer">oleg.grenrus@iki.fi</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">I cannot see any justification for that instance<br>
<br>
-- | @since 4.11.0.0<br>
instance Fail.MonadFail (ST s) where<br>
fail s = errorWithoutStackTrace s<br>
<br>
If someone wants to fail pattern matches in `ST s`, please do that <br>
explicitly.<br>
<br>
I suggest and propose the removal without any deprecation period. If <br>
someone depends on this behavior, they ought to fix they code <br>
immediately: it's straight forward compiler type-error driven refactoring.<br>
<br>
Note: compatibility package <br>
<a href="https://hackage.haskell.org/package/fail-4.9.0.0/docs/Control-Monad-Fail.html" rel="noreferrer noreferrer" target="_blank">https://hackage.haskell.org/package/fail-4.9.0.0/docs/Control-Monad-Fail.html</a> <br>
doesn't have that instance, so I suspect not-that many use(d) that instance.<br>
<br>
Discussion period: 2 weeks (until Monday 2019-12-09).<br>
<br>
- Oleg<br>
<br>
P.S. you might run into problems with <br>
<a href="https://gitlab.haskell.org/ghc/ghc/issues/15681" rel="noreferrer noreferrer" target="_blank">https://gitlab.haskell.org/ghc/ghc/issues/15681</a> bug/miss-feature, but <br>
there's always a workaround to write code using explicit matching <br>
combinator, so it's not a show stopper.<br>
<br>
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