Revert "Revert "Revert "Pow takes its power in N."""

This reverts commit d0e2b7c.

Author: robrix

src/Unit/Algebra.hs

@@ -134,7 +134,7 @@ class Dimension (dim :: * -> *)
 instance Dimension I
 
 
-class (Dimension du, Unit du u, Unit du' u') => Pow du du' u (n :: N n') u'
+class (Dimension du, Unit du u, Unit du' u') => Pow du du' u (n :: Nat) u'
   | du u n -> du' u'
   , du du' u' n -> u
   , du' u' u n -> du
@@ -145,10 +145,10 @@ instance Unit I u => Pow I I u n u
 
 -- * Calculation
 
-sqU :: (Pow du dsqu u (FromNat 2) squ, Num a) => u a -> squ a
+sqU :: (Pow du dsqu u 2 squ, Num a) => u a -> squ a
 sqU = pure . join (*) . prj
 
-sqrtU :: (Pow dsqrtu du sqrtu (FromNat 2) u, Floating a) => u a -> sqrtu a
+sqrtU :: (Pow dsqrtu du sqrtu 2 u, Floating a) => u a -> sqrtu a
 sqrtU = pure . sqrt . prj
 
 dotU :: (Num a, Metric v, Unit d u) => v (u a) -> v (u a) -> u a
@@ -206,7 +206,7 @@ infixr 8 :^:
 
 instance Dimension (du :^: m)
 
-instance (Unit du u, Plus m n' o, FromNat n' ~ n, KnownNat m, KnownNat o) => Pow (du :^: m) (du :^: o) (u :^: m) n (u :^: o)
+instance (Unit du u, Plus m n o, KnownNat m, KnownNat o) => Pow (du :^: m) (du :^: o) (u :^: m) n (u :^: o)
 
 instance (Unit du u, KnownNat n) => Unit (du :^: n) (u :^: n) where
   factor = K (getK (factor @_ @u) ^ natVal (Proxy @n))

src/Unit/Count.hs

@@ -4,7 +4,6 @@
 {-# LANGUAGE FlexibleInstances #-}
 {-# LANGUAGE GeneralizedNewtypeDeriving #-}
 {-# LANGUAGE MultiParamTypeClasses #-}
-{-# LANGUAGE PolyKinds #-}
 {-# LANGUAGE ScopedTypeVariables #-}
 {-# LANGUAGE TypeApplications #-}
 {-# LANGUAGE TypeFamilies #-}

src/Unit/Length.hs

@@ -33,7 +33,7 @@ import Unit.Multiple
 data Length a
 
 instance Dimension Length
-instance (Unit Length u, KnownNat n, n' ~ FromNat n) => Pow Length (Length :^: n) u n' (u :^: n)
+instance (Unit Length u, KnownNat n) => Pow Length (Length :^: n) u n (u :^: n)
 
 
 newtype Metres a = Metres { getMetres :: a }

src/Unit/Mass.hs

@@ -32,7 +32,7 @@ import Unit.Multiple
 data Mass a
 
 instance Dimension Mass
-instance (Unit Mass u, KnownNat n, n' ~ FromNat n) => Pow Mass (Mass :^: n) u n' (u :^: n)
+instance (Unit Mass u, KnownNat n) => Pow Mass (Mass :^: n) u n (u :^: n)
 
 
 newtype Grams a = Grams { getGrams :: a }

src/Unit/Power.hs

@@ -32,7 +32,7 @@ import Unit.Multiple
 data Power a
 
 instance Dimension Power
-instance (Unit Power u, KnownNat n, n' ~ FromNat n) => Pow Power (Power :^: n) u n' (u :^: n)
+instance (Unit Power u, KnownNat n) => Pow Power (Power :^: n) u n (u :^: n)
 
 
 newtype Watts a = Watts { getWatts :: a }

src/Unit/Time.hs

@@ -36,7 +36,7 @@ import Unit.Multiple
 data Time a
 
 instance Dimension Time
-instance (Unit Time u, KnownNat n, n' ~ FromNat n) => Pow Time (Time :^: n) u n' (u :^: n)
+instance (Unit Time u, KnownNat n) => Pow Time (Time :^: n) u n (u :^: n)
 
 
 newtype Seconds a = Seconds { getSeconds :: a }