#2953: deriving Functor, Foldable, Traversable
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Reporter: twanvl | Owner: twanvl
Type: feature request | Status: new
Priority: normal | Milestone:
Component: Compiler | Version: 6.11
Severity: normal | Resolution:
Keywords: | Difficulty: Unknown
Testcase: | Os: Unknown/Multiple
Architecture: Unknown/Multiple |
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Changes (by simonpj):
* owner: igloo => twanvl
* difficulty: => Unknown
Comment:
Dear twanval
Thanks for doing this. I've taken a look, polished a little, and will
commit shortly.
What is missing is a section in the user manual describing the changes.
You need a section in 8.5 describing the feature, and suitable update in
the flag-reference parts too. By "describing the feature" I mean that you
should explain what does and doesn't work; in particular, about the
special cases for tuples and functions. I've added some comments in the
code, in `TcGenDeriv` for `Functor` to help myself understand, that may
help as a starting point.
Could you manage to do that? I will commit the patch meanwhile, but it's
really incomplete without the documentation. Many thanks
Simon
PS: Looking at the code, I do agree with you that
* Checking the side conditions
* Generating the constraints
could be combined. Perhaps the `CanDerive` constructor should contain a
list of constraints? If you felt like doing this, great. That would
eliminate one traversal, and tidy up the code a bit.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/2953#comment:5>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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