Seems that by making a class you can "prove" by requiring this isomorphism:
class (To r ~ v, From v ~ r) -- , To (From v :: Rep a x) ~ v)
=> TypeGeneric a (r :: Rep a x) (v :: a)
where
type To r :: a
type From v :: Rep a x
See attachment or [1] for the whole
Hi *,
while working on some related code. I came across a rather peculiar behavior
with GHC built from the current master branch at b2c2e3e8.
After condensing the application quite a bit[1], the test case now produces
8 with ghc 8.2.1 and
-6 with ghc 8.3 @ b2c2e3e8
The sample application
While we're on the topic, I'll mention that at one point I attempted
to modify the singletons [1] library so that it would automatically
generate promoted (i.e., type-level) and singled versions of Generic
instances for any data type that derived Generic. I wasn't successful,
since it turns out
Moritz Angermann writes:
> Hi *,
>
> while working on some related code. I came across a rather peculiar behavior
> with GHC built from the current master branch at b2c2e3e8.
>
Indeed this sounds like a real bug. Can you open a ticket?
Also, it looks like the gist
Moritz Angermann writes:
> Hi *,
>
> while working on some related code. I came across a rather peculiar behavior
> with GHC built from the current master branch at b2c2e3e8.
>
The issue was a bug indeed introduced by the commit you cite below. The
problem was a
Hi!
Before starting with generics support at the type level, please first
improve the generics support at the value level. When I looked at it the
last time, there were some apparent leftovers in the form of types or
type parameters never used. In addition, it seems awkward that you have
to pass
Wow -- Fast work! Do add a test case
Simon
| -Original Message-
| From: ghc-devs [mailto:ghc-devs-boun...@haskell.org] On Behalf Of Ben
| Gamari
| Sent: 01 September 2017 14:53
| To: Moritz Angermann ; GHC developers
| Subject: Re: [broken HEAD] In which
Herbert Valerio Riedel writes:
> Good idea!
>
> ...btw, note that a couple years ago, I set up the little known
>
> http://ghc.haskell.org/ticket/1234
>
> alias... :-)
>
Indeed I noticed that and it almost deterred me from adding the new
alias. However, I am sympathetic
On Fri, Sep 1, 2017 at 2:23 PM, Wolfgang Jeltsch
wrote:
> Hi!
>
> Before starting with generics support at the type level, please first
> improve the generics support at the value level. When I looked at it the
> last time, there were some apparent leftovers in the form
Hello everyone,
Earlier today a contributor requested that we have an easier-to-remember URL
for Trac tickets. Consequently, I've configured ghc.haskell.org to redirect
URLs of the form,
http://ghc.haskell.org/t/$n
to the appropriate Trac ticket. For instance,
Good idea!
...btw, note that a couple years ago, I set up the little known
http://ghc.haskell.org/ticket/1234
alias... :-)
On Fri, Sep 1, 2017 at 8:26 PM, Ben Gamari wrote:
> Hello everyone,
>
> Earlier today a contributor requested that we have an easier-to-remember
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