genericAdaptor does not infer #42
Description
@hesselink I have hit a snag with genericAdaptor. It does not infer properly. For example, if I use p2 I get nice inference behaviour
> p2 (("hello " ++), reverse) ("world", [1..5])
("hello world",[5,4,3,2,1])On the other hand, using genericAdaptor for the same purpose gives the error shown at the bottom of this comment. I managed to add a functional dependency which ends up giving us essentially a -> p. I think what we need is a -> p b c, p b c -> a. I can't see how to achieve this because Rep seems to get in the way.
Do you have any ideas how to address this? @Lysxia, you may also have some clever idea. about this.
Thanks!
genericAdaptor type error:
> genericAdaptor (("hello " ++), reverse) ("world", [1..10])
<interactive>:11:2:
Couldn't match expected type ‘GHC.Generics.M1
GHC.Generics.D
GHC.Generics.D1(,)
(GHC.Generics.M1
GHC.Generics.C
GHC.Generics.C1_0(,)
(GHC.Generics.M1
GHC.Generics.S
GHC.Generics.NoSelector
(GHC.Generics.K1 GHC.Generics.R [Char])
GHC.Generics.:*: GHC.Generics.M1
GHC.Generics.S
GHC.Generics.NoSelector
(GHC.Generics.K1 GHC.Generics.R [a1])))’
with actual type ‘GHC.Generics.Rep a0’
The type variables ‘a0’, ‘a1’ are ambiguous
In the first argument of ‘print’, namely ‘it’
In a stmt of an interactive GHCi command: print it