This bundle cleans up some old and unhelpful
comments about coverage and replaces them with
an explicit test.

The HasDefault constraint removal is incidental;
it was necessary for the first iteration of this
change but is now just an independent cleanup.

2 patches for repository darcs-unstable@darcs.net:/opt/darcs/screened:

patch eea132e5d35684f19ef4991f6029ee6f61e3be99
Author: Ganesh Sittampalam <ganesh@earth.li>
Date:   Fri Aug 11 09:36:12 BST 2023
  * drop unused HasDefault constraint

patch 44a482dd63675820ad2cb190c2b3874e58971036
Author: Ganesh Sittampalam <ganesh@earth.li>
Date:   Fri Aug 11 22:30:05 BST 2023
  * Use property instead of comments about coverage

  It was unclear how to actually do the coverage check
  referred to in the comments.

  The most important part of the comment was about
  commutability which ensures that we get useful
  pairs of patches. This has been replaced with an
  an actual test that uses QuickCheck's coverage
  infrastructure. It also checks that some of the
  commutable pairs change representation when
  commuted.

  The other items were mainly about the actual
  patch contents, which is less likely to be broken
  accidentally, and is also harder to check in a
  generic way.

Attachments

• drop-unused-hasdefault-constraint.dpatch
• patch-preview.txt

Might as well get rid of class HasDefault. 'fromNothing' is now a synonym for
'fromMaybe False' and I chose to inline it because this is clearer.

1 patch for repository http://darcs.net/screened:

patch 74a6bd5430449e1504628e82a5f4716d630e6fc2
Author: Ben Franksen <ben.franksen@online.de>
Date:   Sat Aug 12 13:28:10 CEST 2023
  * harness: eliminate class HasDefault

Attachments

• harness_-eliminate-class-hasdefault.dpatch
• patch-preview.txt

Review: nice idea to make this a property we can test!