#5936: Support for data families in generics
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Reporter: reinerp | Owner: dreixel
Type: feature request | Status: patch
Priority: normal | Milestone:
Component: Compiler | Version: 7.4.1
Keywords: | Os: Unknown/Multiple
Architecture: Unknown/Multiple | Failure: None/Unknown
Difficulty: Unknown | Testcase:
Blockedby: | Blocking:
Related: |
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Comment(by simonpj):
Here's the relevant thread on the libraries list:
[http://www.haskell.org/pipermail/libraries/2012-May/017815.html].
Excerpts:
Reiner: I have tried using GHC's new generic deriving
[http://www.haskell.org/ghc/docs/7.4.1/html/users_guide/generic-
programming.html 2] to derive instances - this is almost possible, but is
blocked by a GHC issue [http://hackage.haskell.org/trac/ghc/ticket/5936
3]. IMHO generic deriving would be the best solution (once it works),
because it works for product types as well as newtypes, and requires no
extra GHC assistance or TH.
Ben: This will be quite nice and it sounds like it should cover nearly all
of the cases I'm interested in. I'm not terribly familiar with generics
support so I'm not sure whether this is possible or not, but it would be
great if there were a way to specify whether an SoA or AoS representation
is derived. This way one could write nearly cache-optimal code while
keeping the mechanics of data layout nicely contained.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/5936#comment:8>
GHC <http://www.haskell.org/ghc/>
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