Type-level generics

Evan Laforge qdunkan at gmail.com
Fri Sep 1 21:57:27 UTC 2017

On Fri, Sep 1, 2017 at 2:23 PM, Wolfgang Jeltsch
<wolfgang-it at jeltsch.info> 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 of types or
> type parameters never used. In addition, it seems awkward that you have

I was just about to complain about this myself, since every year or so
I go fail to figure out GHC.Generics after tripping over lots of out
of date documentation, confusing type aliases, and obsolete aliases,
and wrong examples, but I just looked again and it seems like
GHC.Generics got a major update in ghc 8.  It looks like there's still
one confusing reference to Par0: "Note how Par0 and Rec0 both being
mapped to K1 allows us to define a uniform instance here. " but at
least it's not tangled up in the already very confusing examples and
signatures.  I think that sentence can be deleted entirely now?  I
have no idea what it's trying to express.

So thanks to whoever did that.  I'll give it another try.

More information about the ghc-devs mailing list