[Haskell-cafe] RFC: functor-classes-compat
oleg.grenrus at iki.fi
Tue Dec 13 19:38:07 UTC 2016
On 13.12.2016 21:24, David Feuer wrote:
> On Dec 13, 2016 1:26 PM, "Oleg Grenrus" <oleg.grenrus at iki.fi
> <mailto:oleg.grenrus at iki.fi>> wrote:
> I'm not sure we want `transformers` to depend on `containers` either,
> not even mentioning `vector` and `unordered-containers`. Also
> there are
> people stuck with `transformers-0.4` (GHC 7.10).
> Good point, although practically speaking, containers currently
> *can't* depend on transformers, because transformers is not currently
> a GHC boot package. There'll probably be room for your compat package
> for a while, but you'll have to chase those bounds :-/.
transformers *is* boot package, `ghc` package depends on transformers
directly (since GHC 7.6):
$ ghc-pkg describe ghc
array-0.5.1.1 base-18.104.22.168 binary-0.8.3.0 bytestring-0.10.8.1
containers-0.5.7.1 directory-22.214.171.124 filepath-126.96.36.199
ghc-boot-8.0.1 ghci-8.0.1 hoopl-188.8.131.52 hpc-0.6.0.3
process-184.108.40.206 template-haskell-220.127.116.11 time-18.104.22.168
> > Current implementations are naive, but more obviously correct.
> > More than what?
> It seems that implementation for Data.Map is indeed "check size,
> lists", but e.g for vector it uses streaming framework to make things
> fuse, I still use "check size, compare lists" approach.
> I believe the only containers structures with non-boring instances of
> any of those classes are Data.IntMap, Data.IntSet, and Data.Tree.
IntSet is :: *
> Side question: why doesn't Read1 have the ReadPrec-based methods that
> Read does?
I have been wondering the same
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