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Merged
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Oct 10, 2025
Merged

Support Semigroup [a] (etc) #104

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16 changes: 12 additions & 4 deletions src/Hell.hs
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Original file line number Diff line number Diff line change
Expand Up @@ -748,9 +748,10 @@ tc (UForall _ forallLoc _ _ fall _ _ reps0) _env = go reps0 fall
-- At some point you have to decide on the kinds of things. This
-- function handles a few common cases for instance head types:
--
-- Int :: Type (common case)
-- Either :: Type -> Type -> Type (rare case)
-- Mod :: (Type -> Type) -> Type -> Type (only one example as of writing this comment)
-- Int :: Type (common case)
-- [] :: Type -> Type (less common case)
-- Either :: Type -> Type -> Type (rare case)
-- Mod :: (Type -> Type) -> Type -> Type (only one example as of writing this comment)
withClassConstraint ::
forall g k (c :: k -> Constraint) (a :: k).
HSE.SrcSpanInfo ->
Expand All @@ -762,6 +763,12 @@ withClassConstraint ::
Either TypeCheckError (Typed (Term g))
withClassConstraint forallLoc reps rep crep f go =
if
-- Cases that look like: Semigroup (Vector (e :: *))
-- Note: the kinds are limited to this exact specification in the signature above.
| Type.App t _ <- rep,
Just Type.HRefl <- Type.eqTypeRep (typeRepKind t) (TypeRep @(Type -> Type)),
Just dict <- resolve1 (Type.App crep rep) crep t instances ->
go reps (withDict dict f)
-- Cases that look like: Monad (Either (e :: *) (a :: *))
-- Note: the kinds are limited to this exact specification in the signature above.
| Type.App t _ <- rep,
Expand Down Expand Up @@ -855,7 +862,8 @@ instances =
instance1 @Monoid @[],
instance2 @Semigroup @Options.Mod,
instance0 @Semigroup @Text,
instance1 @Semigroup @Vector
instance1 @Semigroup @Vector,
instance1 @Semigroup @[]
]

--------------------------------------------------------------------------------
Expand Down