From: Xavier Dectot <xavier@wheredoibegin.fr>
Date: Sun, 16 Mar 2025 21:30:41 +0100
Subject: [PATCH] b

--- a/Numeric/NumType.lhs
+++ b/Numeric/NumType.lhs
@@ -45,6 +45,7 @@ instances (and possibly additional unidentified GHC extensions).
 >            , EmptyDataDecls
 >            , FunctionalDependencies
 >            , MultiParamTypeClasses
+>            , FlexibleContexts
 >            , FlexibleInstances
 >            , DeriveDataTypeable
 > #-}
@@ -233,14 +234,14 @@ When adding to a non-Zero number our strategy is to "transfer" type
 constructors from the first type to the second type until the first
 type is Zero. We use the 'Succ' class to do this.
 
-> instance (PosTypeI a, Succ b c, Add a c d) => Add (Pos a) b d
-> instance (NegTypeI a, Succ c b, Add a c d) => Add (Neg a) b d
+> instance (NumTypeI b, NumTypeI d, PosTypeI a, Succ b c, Add a c d) => Add (Pos a) b d
+> instance (NumTypeI b, NumTypeI d, NegTypeI a, Succ c b, Add a c d) => Add (Neg a) b d
 
 We define our helper class for subtraction analogously.
 
-> instance (NumType a) => Sub a Zero a
-> instance (Succ a' a, PosTypeI b, Sub a' b c) => Sub a (Pos b) c
-> instance (Succ a a', NegTypeI b, Sub a' b c) => Sub a (Neg b) c
+> instance (NumTypeI a) => Sub a Zero a
+> instance (NumTypeI a, NumTypeI c, Succ a' a, PosTypeI b, Sub a' b c) => Sub a (Pos b) c
+> instance (NumTypeI a, NumTypeI c, Succ a a', NegTypeI b, Sub a' b c) => Sub a (Neg b) c
 
 While we cold have defined a single 'Sub' instance using negation and
 addition.
@@ -291,7 +292,7 @@ positive. We recursively subtract the denominator from nominator
 while incrementing the result, until we reach the zero case.
 
 > instance ( Sum n' (Pos n'') (Pos n)
->          , Div n'' (Pos n') n''', PosTypeI n''')
+>          , Div n'' (Pos n') n''', PosTypeI n, PosTypeI n', PosTypeI n''')
 >       => Div (Pos n) (Pos n') (Pos n''')
 
 Now we tackle cases with negative numbers involved. We trivially
@@ -303,12 +304,12 @@ appropriate.
 >          , Div (Pos p) (Pos p') (Pos p'')
 >          , PosTypeI p'')
 >       => Div (Neg n) (Neg n') (Pos p'')
-> instance ( NegTypeI n, Negate n p'
+> instance ( NegTypeI n, NegType n'', Negate n p'
 >          , Div (Pos p) (Pos p') (Pos p'')
 >          , Negate (Pos p'') (Neg n'')
 >          , PosTypeI p)
 >       => Div (Pos p) (Neg n) (Neg n'')
-> instance ( NegTypeI n, Negate n p'
+> instance ( NegTypeI n, NegType n'', Negate n p'
 >          , Div (Pos p') (Pos p) (Pos p'')
 >          , Negate (Pos p'') (Neg n'')
 >          , PosTypeI p)
-- 
2.48.1