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-rw-r--r--src/Data/Array/Nested/Internal/Shape.hs4
1 files changed, 4 insertions, 0 deletions
diff --git a/src/Data/Array/Nested/Internal/Shape.hs b/src/Data/Array/Nested/Internal/Shape.hs
index b7bbf4c..59f2c9a 100644
--- a/src/Data/Array/Nested/Internal/Shape.hs
+++ b/src/Data/Array/Nested/Internal/Shape.hs
@@ -34,6 +34,7 @@ import Data.Kind (Type, Constraint)
import Data.Monoid (Sum(..))
import Data.Proxy
import Data.Type.Equality
+import GHC.Exts (withDict)
import GHC.IsList (IsList)
import GHC.IsList qualified as IsList
import GHC.TypeLits
@@ -558,6 +559,9 @@ class KnownShS sh where knownShS :: ShS sh
instance KnownShS '[] where knownShS = ZSS
instance (KnownNat n, KnownShS sh) => KnownShS (n : sh) where knownShS = natSing :$$ knownShS
+withKnownShS :: forall sh r. ShS sh -> (KnownShS sh => r) -> r
+withKnownShS sh = withDict @(KnownShS sh) sh
+
shsKnownShS :: ShS sh -> Dict KnownShS sh
shsKnownShS ZSS = Dict
shsKnownShS (SNat :$$ sh) | Dict <- shsKnownShS sh = Dict