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Support scoped type variables in class/instance declarations
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Although #573 added some support for promoting/singling uses of scoped type
variables, it did not properly support scoped type variables in class or
instance declarations due to an oversight. This patch aims to correct that
oversight.

The key tricks to making this work are:

* When promoting class or instance methods, we explicitly quantify the type
  variables in the "helper" type family so that we can bind them on the
  left-hand sides of the promoted type family equations.
* In addition, we take care to only bring the _scoped_ type variables into
  scope over the right-hand sides of the promoted type family equations.

See the new `Note [Scoped type variables and class methods]` in
`Data.Singletons.TH.Promote.Monad` for the full details.

Fixes #581.
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RyanGlScott committed Jun 6, 2024
1 parent 0c3c7dd commit e854192
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Showing 23 changed files with 1,302 additions and 571 deletions.
1 change: 1 addition & 0 deletions singletons-base/tests/SingletonsBaseTestSuite.hs
Original file line number Diff line number Diff line change
Expand Up @@ -152,6 +152,7 @@ tests =
, compileAndDumpStdTest "T563"
, compileAndDumpStdTest "T567"
, compileAndDumpStdTest "T571"
, compileAndDumpStdTest "T581"
, compileAndDumpStdTest "T585"
, compileAndDumpStdTest "TypeAbstractions"
],
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Original file line number Diff line number Diff line change
Expand Up @@ -115,31 +115,31 @@ Singletons/BoundedDeriving.hs:(0,0)-(0,0): Splicing declarations
instance PBounded Foo2 where
type MinBound = MinBound_0123456789876543210Sym0
type MaxBound = MaxBound_0123456789876543210Sym0
type MinBound_0123456789876543210 :: Foo3 a
type MinBound_0123456789876543210 :: forall a. Foo3 a
type family MinBound_0123456789876543210 @a :: Foo3 a where
MinBound_0123456789876543210 = Apply Foo3Sym0 MinBoundSym0
type MinBound_0123456789876543210Sym0 :: Foo3 a
MinBound_0123456789876543210 @a = Apply Foo3Sym0 MinBoundSym0
type MinBound_0123456789876543210Sym0 :: forall a. Foo3 a
type family MinBound_0123456789876543210Sym0 @a :: Foo3 a where
MinBound_0123456789876543210Sym0 = MinBound_0123456789876543210
type MaxBound_0123456789876543210 :: Foo3 a
type MaxBound_0123456789876543210 :: forall a. Foo3 a
type family MaxBound_0123456789876543210 @a :: Foo3 a where
MaxBound_0123456789876543210 = Apply Foo3Sym0 MaxBoundSym0
type MaxBound_0123456789876543210Sym0 :: Foo3 a
MaxBound_0123456789876543210 @a = Apply Foo3Sym0 MaxBoundSym0
type MaxBound_0123456789876543210Sym0 :: forall a. Foo3 a
type family MaxBound_0123456789876543210Sym0 @a :: Foo3 a where
MaxBound_0123456789876543210Sym0 = MaxBound_0123456789876543210
instance PBounded (Foo3 a) where
type MinBound = MinBound_0123456789876543210Sym0
type MaxBound = MaxBound_0123456789876543210Sym0
type MinBound_0123456789876543210 :: Foo4 a b
type MinBound_0123456789876543210 :: forall a b. Foo4 a b
type family MinBound_0123456789876543210 @a @b :: Foo4 a b where
MinBound_0123456789876543210 = Foo41Sym0
type MinBound_0123456789876543210Sym0 :: Foo4 a b
MinBound_0123456789876543210 @a @b = Foo41Sym0
type MinBound_0123456789876543210Sym0 :: forall a b. Foo4 a b
type family MinBound_0123456789876543210Sym0 @a @b :: Foo4 a b where
MinBound_0123456789876543210Sym0 = MinBound_0123456789876543210
type MaxBound_0123456789876543210 :: Foo4 a b
type MaxBound_0123456789876543210 :: forall a b. Foo4 a b
type family MaxBound_0123456789876543210 @a @b :: Foo4 a b where
MaxBound_0123456789876543210 = Foo42Sym0
type MaxBound_0123456789876543210Sym0 :: Foo4 a b
MaxBound_0123456789876543210 @a @b = Foo42Sym0
type MaxBound_0123456789876543210Sym0 :: forall a b. Foo4 a b
type family MaxBound_0123456789876543210Sym0 @a @b :: Foo4 a b where
MaxBound_0123456789876543210Sym0 = MaxBound_0123456789876543210
instance PBounded (Foo4 a b) where
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12 changes: 7 additions & 5 deletions singletons-base/tests/compile-and-dump/Singletons/Classes.golden
Original file line number Diff line number Diff line change
Expand Up @@ -159,10 +159,10 @@ Singletons/Classes.hs:(0,0)-(0,0): Splicing declarations
type family (<=>@#@$$$) @a (a0123456789876543210 :: a) (a0123456789876543210 :: a) :: Ordering where
(<=>@#@$$$) a0123456789876543210 a0123456789876543210 = (<=>) a0123456789876543210 a0123456789876543210
infix 4 <=>@#@$$$
type TFHelper_0123456789876543210 :: a -> a -> Ordering
type TFHelper_0123456789876543210 :: forall a. a -> a -> Ordering
type family TFHelper_0123456789876543210 @a (a :: a) (a :: a) :: Ordering where
TFHelper_0123456789876543210 a_0123456789876543210 a_0123456789876543210 = Apply (Apply MycompareSym0 a_0123456789876543210) a_0123456789876543210
type TFHelper_0123456789876543210Sym0 :: (~>) a ((~>) a Ordering)
TFHelper_0123456789876543210 @a (a_0123456789876543210 :: a) (a_0123456789876543210 :: a) = Apply (Apply MycompareSym0 a_0123456789876543210) a_0123456789876543210
type TFHelper_0123456789876543210Sym0 :: forall a. (~>) a ((~>) a Ordering)
data TFHelper_0123456789876543210Sym0 :: (~>) a ((~>) a Ordering)
where
TFHelper_0123456789876543210Sym0KindInference :: SameKind (Apply TFHelper_0123456789876543210Sym0 arg) (TFHelper_0123456789876543210Sym1 arg) =>
Expand All @@ -171,7 +171,8 @@ Singletons/Classes.hs:(0,0)-(0,0): Splicing declarations
instance SuppressUnusedWarnings TFHelper_0123456789876543210Sym0 where
suppressUnusedWarnings
= snd ((,) TFHelper_0123456789876543210Sym0KindInference ())
type TFHelper_0123456789876543210Sym1 :: a -> (~>) a Ordering
type TFHelper_0123456789876543210Sym1 :: forall a. a
-> (~>) a Ordering
data TFHelper_0123456789876543210Sym1 (a0123456789876543210 :: a) :: (~>) a Ordering
where
TFHelper_0123456789876543210Sym1KindInference :: SameKind (Apply (TFHelper_0123456789876543210Sym1 a0123456789876543210) arg) (TFHelper_0123456789876543210Sym2 a0123456789876543210 arg) =>
Expand All @@ -180,7 +181,8 @@ Singletons/Classes.hs:(0,0)-(0,0): Splicing declarations
instance SuppressUnusedWarnings (TFHelper_0123456789876543210Sym1 a0123456789876543210) where
suppressUnusedWarnings
= snd ((,) TFHelper_0123456789876543210Sym1KindInference ())
type TFHelper_0123456789876543210Sym2 :: a -> a -> Ordering
type TFHelper_0123456789876543210Sym2 :: forall a. a
-> a -> Ordering
type family TFHelper_0123456789876543210Sym2 @a (a0123456789876543210 :: a) (a0123456789876543210 :: a) :: Ordering where
TFHelper_0123456789876543210Sym2 a0123456789876543210 a0123456789876543210 = TFHelper_0123456789876543210 a0123456789876543210 a0123456789876543210
class PMyOrd a where
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25 changes: 15 additions & 10 deletions singletons-base/tests/compile-and-dump/Singletons/DataValues.golden
Original file line number Diff line number Diff line change
Expand Up @@ -51,11 +51,13 @@ Singletons/DataValues.hs:(0,0)-(0,0): Splicing declarations
Complex = Apply (Apply PairSym0 (Apply (Apply PairSym0 (Apply JustSym0 ZeroSym0)) ZeroSym0)) FalseSym0
type family Pr where
Pr = Apply (Apply PairSym0 (Apply SuccSym0 ZeroSym0)) (Apply (Apply (:@#@$) ZeroSym0) NilSym0)
type ShowsPrec_0123456789876543210 :: GHC.Num.Natural.Natural
-> Pair a b -> Symbol -> Symbol
type ShowsPrec_0123456789876543210 :: forall a
b. GHC.Num.Natural.Natural
-> Pair a b -> Symbol -> Symbol
type family ShowsPrec_0123456789876543210 @a @b (a :: GHC.Num.Natural.Natural) (a :: Pair a b) (a :: Symbol) :: Symbol where
ShowsPrec_0123456789876543210 p_0123456789876543210 (Pair arg_0123456789876543210 arg_0123456789876543210) a_0123456789876543210 = Apply (Apply (Apply ShowParenSym0 (Apply (Apply (>@#@$) p_0123456789876543210) (FromInteger 10))) (Apply (Apply (.@#@$) (Apply ShowStringSym0 "Pair ")) (Apply (Apply (.@#@$) (Apply (Apply ShowsPrecSym0 (FromInteger 11)) arg_0123456789876543210)) (Apply (Apply (.@#@$) ShowSpaceSym0) (Apply (Apply ShowsPrecSym0 (FromInteger 11)) arg_0123456789876543210))))) a_0123456789876543210
type ShowsPrec_0123456789876543210Sym0 :: (~>) GHC.Num.Natural.Natural ((~>) (Pair a b) ((~>) Symbol Symbol))
ShowsPrec_0123456789876543210 @a @b (p_0123456789876543210 :: GHC.Num.Natural.Natural) (Pair arg_0123456789876543210 arg_0123456789876543210 :: Pair a b) (a_0123456789876543210 :: Symbol) = Apply (Apply (Apply ShowParenSym0 (Apply (Apply (>@#@$) p_0123456789876543210) (FromInteger 10))) (Apply (Apply (.@#@$) (Apply ShowStringSym0 "Pair ")) (Apply (Apply (.@#@$) (Apply (Apply ShowsPrecSym0 (FromInteger 11)) arg_0123456789876543210)) (Apply (Apply (.@#@$) ShowSpaceSym0) (Apply (Apply ShowsPrecSym0 (FromInteger 11)) arg_0123456789876543210))))) a_0123456789876543210
type ShowsPrec_0123456789876543210Sym0 :: forall a
b. (~>) GHC.Num.Natural.Natural ((~>) (Pair a b) ((~>) Symbol Symbol))
data ShowsPrec_0123456789876543210Sym0 :: (~>) GHC.Num.Natural.Natural ((~>) (Pair a b) ((~>) Symbol Symbol))
where
ShowsPrec_0123456789876543210Sym0KindInference :: SameKind (Apply ShowsPrec_0123456789876543210Sym0 arg) (ShowsPrec_0123456789876543210Sym1 arg) =>
Expand All @@ -64,8 +66,9 @@ Singletons/DataValues.hs:(0,0)-(0,0): Splicing declarations
instance SuppressUnusedWarnings ShowsPrec_0123456789876543210Sym0 where
suppressUnusedWarnings
= snd ((,) ShowsPrec_0123456789876543210Sym0KindInference ())
type ShowsPrec_0123456789876543210Sym1 :: GHC.Num.Natural.Natural
-> (~>) (Pair a b) ((~>) Symbol Symbol)
type ShowsPrec_0123456789876543210Sym1 :: forall a
b. GHC.Num.Natural.Natural
-> (~>) (Pair a b) ((~>) Symbol Symbol)
data ShowsPrec_0123456789876543210Sym1 (a0123456789876543210 :: GHC.Num.Natural.Natural) :: (~>) (Pair a b) ((~>) Symbol Symbol)
where
ShowsPrec_0123456789876543210Sym1KindInference :: SameKind (Apply (ShowsPrec_0123456789876543210Sym1 a0123456789876543210) arg) (ShowsPrec_0123456789876543210Sym2 a0123456789876543210 arg) =>
Expand All @@ -74,8 +77,9 @@ Singletons/DataValues.hs:(0,0)-(0,0): Splicing declarations
instance SuppressUnusedWarnings (ShowsPrec_0123456789876543210Sym1 a0123456789876543210) where
suppressUnusedWarnings
= snd ((,) ShowsPrec_0123456789876543210Sym1KindInference ())
type ShowsPrec_0123456789876543210Sym2 :: GHC.Num.Natural.Natural
-> Pair a b -> (~>) Symbol Symbol
type ShowsPrec_0123456789876543210Sym2 :: forall a
b. GHC.Num.Natural.Natural
-> Pair a b -> (~>) Symbol Symbol
data ShowsPrec_0123456789876543210Sym2 (a0123456789876543210 :: GHC.Num.Natural.Natural) (a0123456789876543210 :: Pair a b) :: (~>) Symbol Symbol
where
ShowsPrec_0123456789876543210Sym2KindInference :: SameKind (Apply (ShowsPrec_0123456789876543210Sym2 a0123456789876543210 a0123456789876543210) arg) (ShowsPrec_0123456789876543210Sym3 a0123456789876543210 a0123456789876543210 arg) =>
Expand All @@ -84,8 +88,9 @@ Singletons/DataValues.hs:(0,0)-(0,0): Splicing declarations
instance SuppressUnusedWarnings (ShowsPrec_0123456789876543210Sym2 a0123456789876543210 a0123456789876543210) where
suppressUnusedWarnings
= snd ((,) ShowsPrec_0123456789876543210Sym2KindInference ())
type ShowsPrec_0123456789876543210Sym3 :: GHC.Num.Natural.Natural
-> Pair a b -> Symbol -> Symbol
type ShowsPrec_0123456789876543210Sym3 :: forall a
b. GHC.Num.Natural.Natural
-> Pair a b -> Symbol -> Symbol
type family ShowsPrec_0123456789876543210Sym3 @a @b (a0123456789876543210 :: GHC.Num.Natural.Natural) (a0123456789876543210 :: Pair a b) (a0123456789876543210 :: Symbol) :: Symbol where
ShowsPrec_0123456789876543210Sym3 a0123456789876543210 a0123456789876543210 a0123456789876543210 = ShowsPrec_0123456789876543210 a0123456789876543210 a0123456789876543210 a0123456789876543210
instance PShow (Pair a b) where
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