For discussion for now - I think this is a natural change following patch1267

1 patch for repository darcs-unstable@darcs.net:screened:

Sat Jun 13 23:24:40 BST 2015  Ganesh Sittampalam <ganesh@earth.li>
  * retire the (:<) type following the change in (:<:)'s argument order
  
  It doesn't make sense to have forward and reverse tuples if the list
  constructors are always in "forward" order.
  
  As there's quite a lot of code to change in a few modules, move it to
  a legacy module Darcs.Patch.CommuteRev for now instead of removing it
  entirely.

Attachments

• patch-preview.txt
• retire-the-____-type-following-the-change-in-______s-argument-order.dpatch
• unnamed

These patches eliminate the :< operator. All tests succeed (here at home).

8 patches for repository http://darcs.net/screened:

patch df471099694cb23dfe28bd3ee046e90d64962cb9
Author: Ben Franksen <benjamin.franksen@helmholtz-berlin.de>
Date:   Sun Jun 14 14:15:30 CEST 2015
  * Darcs.Patch.Depends: replaced :< with :>

patch 64d1cb1beb767cb965ddd51870a734be43946c9a
Author: Ganesh Sittampalam <ganesh@earth.li>
Date:   Sun Jun 14 00:24:40 CEST 2015
  * retire the (:<) type following the change in (:<:)'s argument order
  
  It doesn't make sense to have forward and reverse tuples if the list
  constructors are always in "forward" order.
  
  As there's quite a lot of code to change in a few modules, move it to
  a legacy module Darcs.Patch.CommuteRev for now instead of removing it
  entirely.
  

patch 355acb89d33b767d6812a45feacea5316d593036
Author: Ben Franksen <benjamin.franksen@helmholtz-berlin.de>
Date:   Sun Jun 14 15:49:24 CEST 2015
  * Darcs.Patch.Prim.V1.Commute: replaced :< with :>
  
  Also changed the unit test module Darcs.Test.Patch.Properties.V1Set2
  accordingly.

patch 761abc0e52f8175746153415f0486799161cb2b6
Author: Ben Franksen <benjamin.franksen@helmholtz-berlin.de>
Date:   Sun Jun 14 17:22:23 CEST 2015
  * Darcs.Patch.Prim.V1.Coalesce: replaced :< with :>

patch 4dacd78f11ab72d289765098e32a5dc76f20f211
Author: Ben Franksen <benjamin.franksen@helmholtz-berlin.de>
Date:   Sun Jun 14 18:34:08 CEST 2015
  * Darcs.Test.Patch.Examples.Set1: replaced :< with :>

patch ba1b8e72a50d665c133c992e4fd42d501ae0e7bb
Author: Ben Franksen <benjamin.franksen@helmholtz-berlin.de>
Date:   Sun Jun 14 18:34:50 CEST 2015
  * Darcs.Test.Patch.Properties.V1Set1: replaced :< with :>

patch 5d5d304c0514ff169a851953f6247bda8376f979
Author: Ben Franksen <benjamin.franksen@helmholtz-berlin.de>
Date:   Sun Jun 14 18:35:45 CEST 2015
  * Darcs.Patch.V1.Commute: replaced :< with :>

patch b2743f9082927aee584c8a9686331bbae7e4ba64
Author: Ben Franksen <benjamin.franksen@helmholtz-berlin.de>
Date:   Sun Jun 14 18:35:58 CEST 2015
  * removed no longer needed Darcs.Patch.CommuteRev

Attachments

• darcs_patch_depends_-replaced-__-with-__.dpatch
• patch-preview.txt
• unnamed

Thanks for finishing this off! I'm going to screen this whole lot 
now to avoid future conflicts.

I'm working through your changes checking them as I don't entirely 
trust the tests or witnesses to catch things. So far I've done

      * Darcs.Patch.V1.Commute: replaced :< with :>

Reviewed:

  * Darcs.Test.Patch.Properties.V1Set1: replaced :< with :>
  * Darcs.Test.Patch.Examples.Set1: replaced :< with :>

(not very carefully as they're just tests)

  * Darcs.Patch.Prim.V1.Coalesce: replaced :< with :>
The coalescing code is much clearer with this change!

  * Darcs.Patch.Depends: replaced :< with :>
Trivial comment change only

Thanks for reviewing this. I know it's tedious... ;-)

BTW, this one did give me failing tests after I got it to compile for
the first time. One critical part was the hunk commute code where the
actual work is off-loaded to a helper function that just takes two
ByteStrings. No chance for the type checker! Similar with some of the
unsafe* functions, even though I was warned and thus more careful when
changing code hat called one of those.

Reviewed:

  * Darcs.Patch.Prim.V1.Commute: replaced :< with :>
  
  Also changed the unit test module 
Darcs.Test.Patch.Properties.V1Set2 accordingly.

I'm declaring the whole bundle reviewed now as my initial patch has 
effectively already been discussed.