[GHC] #12833: GHCi

[GHC]

#12833: GHCi
-------------------------------------+-------------------------------------
           Reporter:  Iceland_jack   |             Owner:
               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:
Differential Rev(s):                 |         Wiki Page:
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 In multiline mode you can define a multi-line Haskell function:

 {{{
 Prelude> :set +m
 Prelude> let
 Prelude| f :: Int -> Int
 Prelude| f 0 = 0
 Prelude| f n = n - 1
 Prelude|
 Prelude>
 }}}

 Is there a reason why it couldn't work with other things like

 {{{
 Prelude> :set -XPatternSynonyms
 Prelude> let
 Prelude| pattern A = 'A'
 Prelude|

 <interactive>:27:1: error:
     Illegal pattern synonym declaration for ‘A’
       Pattern synonym declarations are only valid at top level
 }}}

 {{{
 Prelude> let
 Prelude| data A
 Prelude|   = B
 Prelude|   | C Int
 Prelude|

 <interactive>:30:1: error:
     parse error (possibly incorrect indentation or mismatched brackets)
 }}}

 {{{
 Prelude> let
 Prelude| type A = Int
 Prelude|

 <interactive>:48:1: error:
     parse error (possibly incorrect indentation or mismatched brackets)
 }}}

 couldn't work, similar to how they work with `:{` and `:}`:

 {{{
 Prelude> :{
 Prelude| data A
 Prelude|   = B
 Prelude|   | C Int
 Prelude| :}
 Prelude>
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12833>
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