Shouldn't all exercises have ghc-options: -Wall in their package.yaml?

[sshine]

In Space Age I argue in my mentor feedback that one benefit of writing a total function,

orbitalPeriod :: Planet -> Float
orbitalPeriod Mercury = ...
orbitalPeriod Venus = ...
...

is that GHC can warn you in case of missing or duplicate cases, and that this is useful when extending data types over time. But if you add a planet and forget to extend orbitalPeriod, stack test and stack build will not, actually, show this warning.

Which made me think, why don't we add ghc-options: -Wall to package.yaml of all exercises?

[petertseng]

Yes, not only is this a good idea on its own merits, the history supports it as well because exercism/exercism#804 added -Wall to the then-instructions. It seems that was lost on the move to Stack.

[sshine]

I've removed ghc-options: -Wall from all example package.yaml. Before the amend:

$ git diff-tree --no-commit-id --name-only -r HEAD | wc -l
201

$ git diff-tree --no-commit-id --name-only -r HEAD | grep examples | wc -l
105

After the amend:

$ git diff-tree --no-commit-id --name-only -r HEAD | wc -l
96

$ git diff-tree --no-commit-id --name-only -r HEAD | grep examples | wc -l
0

As 96 + 105 = 201, it seems that no other files were affected.

(Actually, I did accidentally commit a rogue file and found it by doing this test. Hooray!)