#4009: can newtype be extended to permit GADT-like declarations
--------------------------------+-------------------------------------------
Reporter: nr | Owner:
Type: feature request | Status: new
Priority: normal | Component: Compiler (Type checker)
Version: 6.12.1 | Keywords: newtype GADT
Os: Linux | Testcase:
Architecture: x86 | Failure: None/Unknown
Patch: 0 |
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I'd like to create the following value constructor without the overhead of
{{{data}}}:
{{{
data B n e x where
B :: Body n -> B n C C
}}}
However, if I ask for {{{newtype}}} instead of {{{data}}} I'm told that a
newtype constructor must have a return type of form {{{T a1 ... an}}}. Is
this restriction fundamental? If not, could it be possible to allow GADT-
like declarations for {{{newtype}}}?
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Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/4009>
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The Glasgow Haskell Compiler
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