Re: [commit: ghc] master: Extend `Foldable` class with `length` and `null` methods (e5cca4a)

Hi, Am Sonntag, den 28.09.2014, 13:07 +0000 schrieb git@git.haskell.org:

commit e5cca4ab246ca2d1ecdd7c39eefd3157547cb6aa Author: Herbert Valerio Riedel Date: Sun Sep 28 13:02:53 2014 +0200

Extend `Foldable` class with `length` and `null` methods

This completes the `Foldable` class by two important operations which this way can be optimised for the underlying structure more easily.

A minor fix for the `containers` submodule was needed to due name clash

Addresses #9621

Reviewed By: ekmett, dfeuer, austin

Differential Revision: https://phabricator.haskell.org/D250

this broke nofib: ==nofib== para: time to compile Main follows... /data1/ghc-builder/logs/ghc-tmp-REV/inplace/bin/ghc-stage2 -O2 -Rghc-timing -H32m -hisuf hi -rtsopts -c Main.lhs -o Main.o Main.lhs:517:32: No instance for (Foldable t0) arising from a use of ‘step’ The type variable ‘t0’ is ambiguous Relevant bindings include par1' :: [t0 a] -> [[t0 a]] (bound at Main.lhs:516:2) Note: there are several potential instances: instance Foldable ((,) a) -- Defined in ‘Data.Foldable’ instance GHC.Arr.Ix i => Foldable (GHC.Arr.Array i) -- Defined in ‘Data.Foldable’ instance Foldable (Either a) -- Defined in ‘Data.Foldable’ ...plus three others In the first argument of ‘fold1’, namely ‘step’ In the second argument of ‘(.)’, namely ‘fold1 step start’ In the second argument of ‘(.)’, namely ‘minWith cost . fold1 step start’ <> Greetings, Joachim -- Joachim “nomeata” Breitner mail@joachim-breitner.de • http://www.joachim-breitner.de/ Jabber: nomeata@joachim-breitner.de • GPG-Key: 0xF0FBF51F Debian Developer: nomeata@debian.org