Noncanonical mappend

[andreasabel]

This warning should be addressed at some point:

Building library for strict-0.4.0.1..
...
[4 of 7] Compiling Data.Strict.Tuple ( src/Data/Strict/Tuple.hs, dist/build/Data/Strict/Tuple.o, dist/build/Data/Strict/Tuple.dyn_o )

src/Data/Strict/Tuple.hs:171:3: warning: [-Wnoncanonical-monoid-instances]
    Noncanonical ‘mappend’ definition detected
    in the instance declaration for ‘Monoid (Pair a b)’.
    ‘mappend’ will eventually be removed in favour of ‘(<>)’
    Either remove definition for ‘mappend’ (recommended) or define as ‘mappend = (<>)’
    See also: https://gitlab.haskell.org/ghc/ghc/-/wikis/proposal/semigroup-monoid
    |
171 |   (x1 :!: y1) `mappend` (x2 :!: y2) = (x1 `mappend` x2) :!: (y1 `mappend` y2)
    |   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

[phadej]

let's disable the warning. CPP is not worth it in this case.

[andreasabel]

let's disable the warning. CPP is not worth it in this case.

So you don't believe what the warning says:

‘mappend’ will eventually be removed in favour of ‘(<>)’

Because if it is true, CPP will be needed anyway...

[phadej]

Because if it is true, CPP will be needed anyway...

Or the lower bound support can be trimmed so it isn't.