[Haskell-cafe] ordNub

Dan Doel dan.doel at gmail.com
Fri Oct 18 20:16:43 UTC 2013

On Fri, Oct 18, 2013 at 3:13 PM, David Thomas <davidleothomas at gmail.com> wrote:
> With such a big speedup and not a lot of downside, I'd really rather it wind
> up central enough to be used in preference to nub wherever possible
> (including in base!).  Perhaps they can duplicate the minimum functionality
> necessary from Data.Set, internally behind the scenes?  Alternatively, maybe
> we can move nub out of base?

The string 'nub' does not appear anywhere (that I can find) in base
outside of Data.List. All occurrences of 'nub' in Data.List are in the
definition and export of nub and nubBy, except one use of nubBy in
unionBy, which cannot switch to ordNub, and would have to have its own
alternate function.

Of all the libraries packaged with GHC, the only one I see that uses
nub outside of tests is Cabal, which already depends on containers.
And in fact, one of the libraries I grepped through _was_ containers,
because it's already about as close as you can get to being in base
without actually being there, and is certainly as close as many other
things will be once we split up base into more packages.

I don't think it's really accurate to suggest that containers is less
core than base. It's not just, 'some library.'

-- Dan

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