[GHC] #13480: GHCi display visible type application

[GHC]

#13480: GHCi display visible type application
-------------------------------------+-------------------------------------
           Reporter:  Iceland_jack   |             Owner:  (none)
               Type:  feature        |            Status:  new
  request                            |
           Priority:  normal         |         Milestone:
          Component:  Compiler       |           Version:  8.0.1
           Keywords:                 |  Operating System:  Unknown/Multiple
       Architecture:                 |   Type of failure:  None/Unknown
  Unknown/Multiple                   |
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:  #8751
Differential Rev(s):                 |         Wiki Page:
-------------------------------------+-------------------------------------
 Similar to #8751, have a way to get GHCi to dump which types an expression
 is applied to:

 {{{
 ghci> :tyapp length [1,2,3]
 length @[] @Integer [1,2,3]
 }}}

 It could also function as the [https://downloads.haskell.org/~ghc/master
 /users-guide/ghci.html#ghci-cmd-:all-types :all-types],
 [https://downloads.haskell.org/~ghc/master/users-guide/ghci.html#ghci-cmd
 -:type-at :type-at] commands where we can specify a region of code (from
 [https://www.researchgate.net/publication
 /282487445_Combining_Deep_and_Shallow_Embedding_of_Domain-
 Specific_Languages?ev=pubitem-pub_cit_inc Combining Deep and Shallow
 Embedding of Domain-Specific Languages])

 {{{#!hs
   fromFunC :: FunC (m (Internal a)) -> Mon m a
   fromFunC m   = M $ \k -> fromFunC Bind m k
 }}}

 displays

 {{{#!hs
   fromFunC :: FunC (m (Internal a)) -> Mon m a
   fromFunC m = M @m @a $ \(k :: a -> FunC (m b)) -> fromFunC @(FunC (m
 (Internal a)) -> (a -> FunC (m b)) -> FunC (m b)) (Bind @m @(Internal a)
 @b) m k
 }}}

 Would be great to get this feature as an IDE support.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13480>
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