Problems getting information and kind from GHC.Prim ~#, ~R#, ...

>>> import GHC.Prim
>>> :bro GHC.Prim
  [...]
type role (~#) nominal nominal
data (~#) (t3 :: a) (t4 :: b)
type role ~P# phantom phantom
data ~P# (t3 :: a) (t4 :: b)
type role (~R#) representational representational
data (~R#) (t3 :: a) (t4 :: b)

getting the kind of ~, ~#, ~~ works fine:

>>> import GHC.Prim
>>> import GHC.Types

>>> :kind (~)
(~) :: k -> k -> Constraint
>>> :kind (~#)
(~#) :: a -> b -> TYPE 'VoidRep
>>> :kind (~~)
(~~) :: j -> k -> Constraint

but # gets incorrectly treated as an operator in ~R# and ~P#:

>>> :kind (~R#)

<interactive>:1:3: error:
    Illegal operator ‘#’ in type ‘~R #’
      Use TypeOperators to allow operators in types

<interactive>:1:3: error:
    Operator applied to too few arguments: ~R #

<interactive>:1:4: error:
    Not in scope: type constructor or class ‘R’

Furthermore while running :info on ~~ and ~# works fine

>>> :info (~~)
class a ~# b => (~~) (a :: j) (b :: k)  -- Defined in ‘GHC.Types’

>>> :info (~#)
type role (~#) nominal nominal
data (~#) (t3 :: a) (t4 :: b)
        -- Defined in ‘GHC.Prim’

the others don't parse

>>> :info (~)

<interactive>:1:2: error: parse error on input ‘~’
>>> :info (~R#)

<interactive>:1:2: error: parse error on input ‘~’
>>> :info (~P#)

<interactive>:1:2: error: parse error on input ‘~’

Trac metadata

Trac field	Value
Version	7.10.3
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	GHCi
Test case
Differential revisions
BlockedBy
Related
Blocking
CC
Operating system
Architecture

mentioned in issue #10059 (closed)

changed weight to 5

added GHCi Tbug Trac import labels

mentioned in issue #12390 (closed)

mentioned in issue #15209 (closed)

The fact that :info doesn't work for (~) is being tracked separately at #10059 (closed).

I'm not surprised that :info (~R#) and :info (~#P) don't work, since I wouldn't expect users to be able to make use of these (see also #15209 (closed), which proposes to remove the ability to query :info (~#).) It's a bit unfortunate that :browse GHC.Prim exposes (~#) and friends—perhaps we could alter :browse to avoid printing them.

Trac metadata

Trac field	Value
Related	- → #10059 (closed), #15209 (closed)

Trac metadata

Trac field	Value
Differential revisions	- → D4801

mentioned in commit 5926b6ed

closed

changed milestone to %8.6.1

Trac metadata

Trac field	Value
Resolution	Unresolved → ResolvedFixed

added Pnormal label