[GHC] #14826: Flatten data types extending other data types in STG

[GHC]

#14826: Flatten data types extending other data types in STG
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        Reporter:  nomeata           |                Owner:  (none)
            Type:  feature request   |               Status:  new
        Priority:  low               |            Milestone:
       Component:  Compiler          |              Version:  8.5
      Resolution:                    |             Keywords:
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 nomeata):

 This might be useful to be able to do
 {{{
 data IntSet = NonEmpty !NonEmptyIntSet | Tip
 data NonEmptyIntSet = Bin … | Leaf …
 }}}
 and get more expressive types than the current
 {{{
 data IntSet = Bin … | Leaf … | Tip
 }}}
 without having to pay a performance penalty for it.

 Or even
 {{{
 data [a] = Nil | NonEmpty !(NEList a)
 data (NEList a) = Cons a [a]
 }}}
 (no, I am not proposing to change the `Prelude` :-))

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14826#comment:1>
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