tiny build fixes

shell.nix

@@ -1,9 +1,7 @@
 let pkgs = import <nixpkgs> {};
 in with pkgs; pkgs.mkShell
   { packages =
-  [ haskell.packages.ghc943.ghc
-    cabal-install
-    zlib
+  [ zlib
     pkg-config
     gobject-introspection
     gtk4

src/splines/Math/Interval/Internal.hs

@@ -6,7 +6,7 @@
 {-# OPTIONS_GHC -Wno-orphans #-}
 
 module Math.Interval.Internal
-  ( 𝕀(𝕀), inf, sup, scaleInterval )
+  ( 𝕀(𝕀, inf, sup), scaleInterval )
   where
 
 -- base
@@ -155,19 +155,17 @@ newtype 𝕀 a = MkI { ival :: Interval.Interval a }
 
 {-# COMPLETE 𝕀 #-}
 pattern 𝕀 :: a -> a -> 𝕀 a
-pattern 𝕀 x y = MkI ( Interval.I ( Rounded x ) ( Rounded y ) )
-
-inf, sup :: 𝕀 a -> a
-inf (𝕀 a _) = a
-sup (𝕀 _ b) = b
+pattern 𝕀 { inf, sup } = MkI ( Interval.I ( Rounded inf ) ( Rounded sup ) )
 
 instance Ring ( 𝕀 Double ) where
   MkI i1 * MkI i2 = MkI $ i1 Prelude.* i2
-  MkI x ^ n = MkI $ Interval.powInt x ( Prelude.fromIntegral n )
+  MkI x ^ n = MkI { ival = Interval.powInt x ( Prelude.fromIntegral n ) }
     -- This is very important, as x^2 is not the same as x * x
     -- in interval arithmetic. This ensures we don't
     -- accidentally use (^) from Prelude.
 
+deriving via ViaPrelude ( 𝕀 Double )
+  instance Floating ( 𝕀 Double )
 deriving via ViaPrelude ( 𝕀 Double )
   instance Transcendental ( 𝕀 Double )