uu-computerscience / uhc-util Goto Github PK

UHC.Util.Utils.sortOn uses the builtin Data.List.sortOn with GHC 7.10 or later. On earlier GHCs, an own custom implementation is used. See https://github.com/UU-ComputerScience/uhc-util/blob/master/src/UHC/Util/Utils.hs#L252-257 .

These two implementations have slightly different strictness, where the Data.List.sortOn version seems to be slightly more strict.

This causes a shuffle error when compiling UHC, see http://hydra.cryp.to/build/787325/nixlog/3/raw . The call to sortOn causing the
problem is at https://github.com/UU-ComputerScience/shuffle/blob/master/src/UHC/Shuffle/Common.hs#L373-382 .

I see two possible solutions:

1. Use the old custom sortOn implementation also for newer GHC versions
2. Fix call sites to not rely on the lazyness of sortOn.
   There are 19 calls to sortOn in UHC plus 2 more in shuffle, but I have no idea if
   any of them rely on the lazyness of sortOn.

@atzedijkstra I prefer the first solution, as hunting down problems with
lazyness/strictness isn't that much fun. Which option do you prefer?

( see also UU-ComputerScience/shuffle#4 .)

UHC depends on uhc-util >=0.1.6.8 && <0.1.7, but the most recent version on Hackage is 0.1.6.7.

For example, in http://hackage.haskell.org/package/uhc-util-0.1.5.3 the changelog is not available.

I couldn't install the development version of the library:

$ cabal install
...
cabal: can't find source for UHC/Util/Hashable in src, dist/build/autogen
Failed to install uhc-util-0.1.5.1

Edit (2016-02-13): I couldn't install using GHC 8.0.1 RC 1 RC 2:

$ cabal unpack uhc-util
$ cd uhc-util-0.1.6.3
$ cabal sandbox init
$ cabal install
...
trying: fclabels-2.0.2.4 (dependency of uhc-util-0.1.6.3)
next goal: template-haskell (dependency of fclabels-2.0.2.4)
rejecting: template-haskell-2.11.0.0/installed-2.1... (conflict: fclabels =>
...

The first blocking issue is sebastiaanvisser/fclabels#27.

If the library is called uhc-util why this repository hasn't the same name?

We are planning to build Agda using Stackage. Please consider to add uhc-util to Stackage. See instructions here.

CC'ing @phile314.