:info no longer shows instances of poly-kinded data families in GHC 9.2+
If you load this program into GHCi:
{-# LANGUAGE PolyKinds #-}
{-# LANGUAGE TypeFamilies #-}
module Bug where
data family D (a :: k)
data instance D Int = DInt
In GHCi 9.0.1, running :info D
will show the data family instance:
$ /opt/ghc/9.0.1/bin/ghci Bug.hs
GHCi, version 9.0.1: https://www.haskell.org/ghc/ :? for help
Loaded GHCi configuration from /home/ryanglscott/.ghci
[1 of 1] Compiling Bug ( Bug.hs, interpreted )
Ok, one module loaded.
λ> :info D
type D :: forall k. k -> *
data family D a
-- Defined at Bug.hs:5:1
data instance D Int = DInt -- Defined at Bug.hs:6:15
In GHCi 9.2.1-alpha1, however, this no longer happens:
$ ~/Software/ghc-9.2.1-alpha1/bin/ghci Bug.hs
GHCi, version 9.2.0.20210331: https://www.haskell.org/ghc/ :? for help
Loaded GHCi configuration from /home/ryanglscott/.ghci
[1 of 1] Compiling Bug ( Bug.hs, interpreted )
Ok, one module loaded.
λ> :info D
type D :: forall k. k -> *
data family D a
-- Defined at Bug.hs:5:1
This regression was introduced in commit aaa5fc21 ( Actually, it was introduced in 3e082f8f (Replace Ord TyLit with nonDetCmpTyLit (#19441)
). cc @int-indexImplement BoxedRep proposal
).