[GHC] #5850: Greater customization of GHCi prompt

[GHC]

#5850: Greater customization of GHCi prompt
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        Reporter:  JamesFisher       |                Owner:  niksaz
            Type:  feature request   |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  GHCi              |              Version:  7.4.1
      Resolution:                    |             Keywords:  newcomer
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #9994             |  Differential Rev(s):  Phab:D2084
       Wiki Page:                    |
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Comment (by Ben Gamari <ben@…>):

 In [changeset:"533037cc58a7c50e1c014e27e8b971d53e7b47bd/ghc" 533037c/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="533037cc58a7c50e1c014e27e8b971d53e7b47bd"
 Greater customization of GHCi prompt

 This patch is trying to redesign the :set prompt option to take not a
 String but a Haskell function, like [String] -> Int -> IO String, where
 [String] is the list of the names of the currently loaded modules and
 Int is the line number. Currently you may set prompt function with
 **:set promt-function [String] -> Int -> IO String** option and old
 version is also available - :set prompt String.

 So, it looks like I've almost completed this patch:

 1) Now we have a lot of escape sequences - 13 to be exact. Most of them
    are similar to bash prompt escape sequences. Thus they are quite handy.

 2) We may use the special escape sequence to call shell functions, for
    example "%call(ls -l -a)".

 3) We may use :set prompt-function to set PFunction to handle prompt.
    It is just [String] -> Int -> IO String.

 Reviewers: erikd, austin, mpickering, bgamari

 Reviewed By: mpickering, bgamari

 Subscribers: mpickering, thomie

 Differential Revision: https://phabricator.haskell.org/D2084

 GHC Trac Issues: #5850
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/5850#comment:18>
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