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List:       haskell-cafe
Subject:    ovelapping instances under control
From:       Ralf Laemmel <Ralf.Laemmel () cwi ! nl>
Date:       2003-05-30 19:04:23
Message-ID: 3ED7AB37.55BEFE12 () cwi ! nl
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Hi,

I think that there is consensus regarding the
usefulness of overlapping instances. But it is
a pitty that the -fallow-overlapping-instances
declaration is so pervasive. I mean:

- If I deal with several classes, only few of
them require overlapping instances, then I would
like to restrict -fallow to the relevant classes.

- If I compile a module A with overlapping instances
allowed, and I import A into B, then I don't want
to be forced to allow overlapping instances in B
unless B by itself wants to produce overlaps.

Did I miss anything?
If not, would that be difficult (formally, technically)?

Ralf
 

-- 
Ralf Laemmel
VU & CWI, Amsterdam, The Netherlands
http://www.cs.vu.nl/~ralf/
http://www.cwi.nl/~ralf/

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