Prelude and (:) and []((:), []) bugs?

Simon Peyton-Jones simonpj@microsoft.com
Fri, 21 Sep 2001 01:22:31 -0700


It's hard to distinguish a constructor from a class in an
export list.=20

S

| -----Original Message-----
| From: Alastair David Reid [mailto:reid@cs.utah.edu]=20
| Sent: 20 September 2001 19:38
| To: Simon Marlow
| Cc: Ian Lynagh; haskell@haskell.org; hugs-bugs@haskell.org
| Subject: Re: Prelude and (:) and []((:), []) bugs?
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| > Ah, I forgot that you can't export a constructor on its own.
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| You can't?
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| I probably knew this once but looking at it now, it seems=20
| kinda surprising.  Haskell's module system is supposed to be=20
| just namespace control --nothing more-- so why is it=20
| preventing me from doing something which is perfectly safe=20
| and well-defined?
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| I'll readily agree that there's no strong motivation for=20
| exporting a constructor on its own (I think the only reason=20
| Hugs allows it is just so we can export (:) from the Prelude)=20
| but what is the motivation for disallowing it?
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| --=20
| Alastair Reid        reid@cs.utah.edu       =20
| http://www.cs.utah.edu/~reid/
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