[GHC] #15887: Ideas for a better GHCi editing experience

[GHC]

#15887: Ideas for a better GHCi editing experience
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        Reporter:  Anchpop           |                Owner:  (none)
            Type:  feature request   |               Status:  new
        Priority:  high              |            Milestone:  Research
                                     |  needed
       Component:  Compiler          |              Version:  8.6.2
      Resolution:                    |             Keywords:  QoL
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by Anchpop):

 https://github.com/prompt-toolkit/ptpython has all the features I
 described here (video at https://youtu.be/XDgIDslyAFM?t=4 ). While the
 features might be common in IDEs, that doesn't mean they would be useless
 in GHCi. I miss having these features every time I use GHCi.

 Another benefit is that it would be easier for beginners to learn. Imagine
 a beginner enters the following:

 Prelude> myHead [] = Nothing
 Prelude> myHead (x:xs) = Just x

 They'll be left scratching their head after their program crashes when
 they enter `myHead []`! My suggestion would have their `myHead` first
 definition automatically trigger multiline mode, so they could easily
 continue pattern matching. Teaching beginners about `:{` adds complexity
 and clutter to a language as simple and intuitive as Haskell.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15887#comment:3>
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