Fix Either/FilterValue compiler error #1
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It looks like in old versions of persistent (e.g. https://hackage.haskell.org/package/persistent-2.9.2/docs/Database-Persist-Types.html), Filter had these constructors: ``` data Filter record = forall typ. PersistField typ => Filter { filterField :: EntityField record typ , filterValue :: Either typ [typ] -- FIXME , filterFilter :: PersistFilter -- FIXME } | FilterAnd [Filter record] -- ^ convenient for internal use, not needed for the API | FilterOr [Filter record] | BackendFilter (BackendSpecificFilter (PersistEntityBackend record) record) ``` but in newer versions, it changed (https://hackage.haskell.org/package/persistent-2.10.4/docs/Database-Persist-Types.html#t:Filter): ``` data Filter record = forall typ. PersistField typ => Filter { filterField :: EntityField record typ , filterValue :: FilterValue typ , filterFilter :: PersistFilter -- FIXME } | FilterAnd [Filter record] -- ^ convenient for internal use, not needed for the API | FilterOr [Filter record] | BackendFilter (BackendSpecificFilter (PersistEntityBackend record) record) ``` resulting in this compiler error: ``` /Users/maximiliantagher/Documents/Clones/Haskell/persistent-iproute/Database/Persist/IP.hs:42:71: error: • Couldn't match expected type ‘FilterValue IP’ with actual type ‘Either IP b0’ • In the second argument of ‘Filter’, namely ‘(Left ip)’ In the expression: Filter (unsafeCoerce field :: EntityField record IP) (Left ip) (BackendSpecificFilter ">>") In an equation for ‘>.>.’: field >.>. ip = Filter (unsafeCoerce field :: EntityField record IP) (Left ip) (BackendSpecificFilter ">>") | 42 | field >.>. ip = Filter (unsafeCoerce field :: EntityField record IP) (Left ip) (BackendSpecificFilter ">>") | ^^^^^^^ ``` `FilterValue` is defined like this: ``` data FilterValue typ where FilterValue :: typ -> FilterValue typ FilterValues :: [typ] -> FilterValue typ UnsafeValue :: forall a typ. PersistField a => a -> FilterValue typ ``` So, my reading of the situation is that it needed a third constructor, so what was previously `Left`/`Right` is now `FilterValue`/`FilterValues`, and just a switchout is necessary. I compiled with: ``` extra-deps: [persistent-2.10.4] ``` to confirm this fixes the compilation error. I haven't tested this at runtime though.
MaxGabriel
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Oh wait, I need to either use CPP or add a constraint on using a more recent persistent Edit: went with CPP |
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Separately, would you support editing package metadata to require < 2.10.0 for persistent? https://hackage.haskell.org/package/persistent-iproute-0.2.3/persistent-iproute.cabal/edit |
MaxGabriel
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Nov 29, 2019
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| # Here starts the actual work to be performed for the package under test; any command which exits with a non-zero exit code causes the build to fail. | ||
| script: | ||
| - if [ -f configure.ac ]; then autoreconf -i; fi | ||
| - cabal configure --enable-tests --enable-benchmarks -v2 --disable-shared # -v2 provides useful information for debugging |
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--enable-tests --enable-benchmarks was causing errors on HEAD. I think it's fine to just remove it—this package doesn't have tests or benchmarks anyway
MaxGabriel
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Nov 29, 2019
| @@ -5,8 +5,6 @@ sudo: false | |||
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| matrix: | |||
| include: | |||
| - env: CABALVER=1.18 GHCVER=7.8.4 | |||
| addons: {apt: {packages: [cabal-install-1.18,ghc-7.8.4], sources: [hvr-ghc]}} | |||
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aeson-iproute wasn't compiling on old GHC. I think it's fine to drop this—GHC 7.8 dates back to 2014
Just did it. Would you squash this PR into a single commit please? |
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Oh, you can squash right from the Github UI now:
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Squashed and released! |
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It looks like in old versions of persistent (e.g. https://hackage.haskell.org/package/persistent-2.9.2/docs/Database-Persist-Types.html), Filter had these constructors:
but in newer versions, it changed (https://hackage.haskell.org/package/persistent-2.10.4/docs/Database-Persist-Types.html#t:Filter):
resulting in this compiler error:
FilterValueis defined like this:So, my reading of the situation is that it needed a third constructor, so what was previously
Left/Rightis nowFilterValue/FilterValues, and just a switchout is necessary. I compiled with:to confirm this fixes the compilation error.
I haven't tested this at runtime though.