GHCi support for type/data families should match that of related features

Currently, GHCi queries are not as helpful with type and data families as they are with type synonyms or class instances. Consider this module:

{-# LANGUAGE FunctionalDependencies #-}
{-# LANGUAGE MultiParamTypeClasses #-}
{-# LANGUAGE TypeFamilies #-}

type family TF a
type instance TF Bool = Char
type instance TF Int  = Bool

data family DF a
data instance DF Bool = DFC Char
data instance DF Int  = DFB Bool

class FD a b | a -> b
instance FD Bool Char
instance FD Int  Bool

type TS a = (a,a)

and compare the output of :info for these items:

*Main> :i TS
type TS a = (a, a)
        -- Defined at C:\Users\claus\Desktop\tmp\fd-tf\tf-df-info.hs:17:5-6
*Main> :i TF
type family TF a :: *
        -- Defined at C:\Users\claus\Desktop\tmp\fd-tf\tf-df-info.hs:5:12-13
*Main> :i FD
class FD a b | a -> b
        -- Defined at C:\Users\claus\Desktop\tmp\fd-tf\tf-df-info.hs:13:6-7
instance FD Bool Char
  -- Defined at C:\Users\claus\Desktop\tmp\fd-tf\tf-df-info.hs:14:9-20
instance FD Int Bool
  -- Defined at C:\Users\claus\Desktop\tmp\fd-tf\tf-df-info.hs:15:9-20
*Main> :i DF
data family DF a
        -- Defined at C:\Users\claus\Desktop\tmp\fd-tf\tf-df-info.hs:9:12-13

Neither the type family definition nor the data family instances are listed. If we try :browse instead

*Main> :browse
type family TF a :: *
data family DF a
data instance Main.R:DFBool Bool = DFC Char
data instance Main.R:DFInt Int = DFB Bool
class FD a b | a -> b
type TS a = (a, a)

we get some form of info about the data family instances, though no instances are listed for the plain old class, and the data family instance info shows internal encoding details.

Trac metadata

Trac field	Value
Version	6.12.3
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	GHCi
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