Fix the visible type arguments of proxy# #87
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Visibility of the kind argument changed in https://gitlab.haskell.org/ghc/ghc/-/commit/012257c15f584069500af2953ab70856f9a1470e . This makes capability compatible with GHC 8.10 .
```
src/Capability/Reflection.hs:68:3: error:
• Variables ‘k, tag’ occur more often
in the constraint ‘Reifies s (Reified tag c m)’
than in the instance head ‘c (Reflected s c m)’
(Use UndecidableInstances to permit this)
• In the quantified constraint ‘forall s.
Reifies s (Reified tag c m) =>
c (Reflected s c m)’
In the type signature:
interpret_ :: forall tag c m a.
(Monad m,
forall s. Reifies s (Reified tag c m) => c (Reflected s c m)) =>
Reified tag c m -> (forall m'. c m' => m' a) -> m a
|
68 | forall tag c m a.
| ^^^^^^^^^^^^^^^^^...
```
```
examples/Error.hs:84:15: error:
• Illegal polymorphic type:
forall (m' :: * -> *).
(HasCatch "parser" inner0 m', () :: Constraint) =>
m' a
Perhaps you intended to use RankNTypes
• When checking the inferred type
wrapParserError :: forall a.
(forall (m' :: * -> *).
(HasCatch "parser" inner0 m', () :: Constraint) =>
m' a)
-> m0 a
In the second argument of ‘catch’, namely
‘do let wrapParserError
= wrapError
@"parser" @(Rename "ParserError" :.: Ctor "ParserError" "calc")
@'[]
wrapMathError
= wrapError
@"math" @(Rename "MathError" :.: Ctor "MathError" "calc") @'[]
num <- wrapParserError $ parseNumber input
root <- wrapMathError $ sqrtNumber num
liftIO $ putStrLn $ "sqrt = " ++ show root’
In a stmt of a 'do' block:
catch
@"calc"
do let wrapParserError
= wrapError
@"parser" @(Rename "ParserError" :.: Ctor "ParserError" "calc")
@'[]
wrapMathError
= wrapError
@"math" @(Rename "MathError" :.: Ctor "MathError" "calc") @'[]
num <- wrapParserError $ parseNumber input
root <- wrapMathError $ sqrtNumber num
liftIO $ putStrLn $ "sqrt = " ++ show root
\ e -> liftIO $ putStrLn $ "Error: " ++ show e
|
84 | let wrapParserError = wrapError @"parser"
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^...
```
aherrmann
approved these changes
Mar 15, 2021
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aherrmann
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I've updated the version bounds and Nix shell for GHC 8.10.4 and to match Stackage LTS 17.4.
Additional fixes that were required:
- Use
Typeinstead of* - Enable
RankNTypesin one example. - Enable
UndecidableInstancesinCapability.Reflection. - Remove a few now redundant imports.
aspiwack
commented
Mar 15, 2021
|
|
||
| -- | Deriving two capabilities from the record fields of @MonadReader@. | ||
| newtype CountLogM m (a :: *) = CountLogM (ReaderT CountLogCtx m a) | ||
| newtype CountLogM m (a :: Type) = CountLogM (ReaderT CountLogCtx m a) |
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We should also use toplevel kind signatures. But let's worry about that another day.
| -- returns a 'Constraint'. Examples of capabilities includ: @HasReader "foo" | ||
| -- Int@, @MonadIO@, … | ||
| type Capability = (* -> *) -> Constraint | ||
| type Capability = (Type -> Type) -> Constraint |
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It probably would have been less noisy to enable -XStarIsKind. But at least, now, we are more future-proof.
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Visibility of the kind argument changed in
https://gitlab.haskell.org/ghc/ghc/-/commit/012257c15f584069500af2953ab70856f9a1470e
.
This makes capability compatible with GHC 8.10 .
We still need to change the dependencies to be recent enough.