[GHC] #13757: Are you for or against writing "otherwise" as a keyword?

26 May 2017

      #13757: Are you for or against writing "otherwise" as a keyword?
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           Reporter:  vanto          |             Owner:  (none)
               Type:  feature        |            Status:  new
  request                            |
           Priority:  normal         |         Milestone:
          Component:  Compiler       |           Version:  8.0.2
           Keywords:                 |  Operating System:  Unknown/Multiple
       Architecture:                 |   Type of failure:  Poor/confusing
  Unknown/Multiple                   |  error message
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):                 |         Wiki Page:
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 {{{otherwise}}} is frequently used and therefore should have been written
 as a keyword.\\

 {{{otherwise}}} was coded in prelude like this {{{otherwise = True}}}\\
 So what is the reason that {{{otherwise}}} was not coded as a keyword?\\
 \\
 To understand you have to go back. It seems that this has been done to
 minimize the number of keywords.\\

 Today it seems surprising. And I wonder why we wrote the conditional
 expression with {{{if}}}{{{then}}}{{{else}}}?
 That's three additional keywords.\\
 \\
 It would have been better to write the conditional expression as in Sasl
 {{{condition -> exp1 ; exp22}}} (By adapting the operators of course.)\\
 Let's go back to {{{otherwise}}} . And take a look at this code.\\

 {{{
 otherwise :: Bool
 otherwise = Prelude.otherwise

 sig :: Integer -> Integer
 sig n  | a   = -1
          | b   = 0
          | Main.otherwise = 1
    where { a = n < 0;
                 b = n == 0 }

 z :: Bool
 z = if Main.otherwise == Prelude.otherwise then True else False

 main :: IO ()
 main = do {
                  print (sig 0);
                  print (z) }

 }}}
 This code works but the compiler result is different by adding or removing
 the first two lines of code.\\
 For me it is urgent that {{{otherwise}}} become a keyword as in Miranda.

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Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13757
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