From f1cba7cebf73e429dbdfa67c88161300bc5e318e Mon Sep 17 00:00:00 2001
From: Christiaan Baaij <christiaan.baaij@gmail.com>
Date: Fri, 14 Sep 2018 14:10:03 +0100
Subject: [PATCH] Move `Div` and `Mod` `KnownNat2` instances

Ensures that the `knownnat` solver can solve `KnownNat`
constraints for the GHC 8.4+ `Div` and `Mod` type families
without having the user import `GHC.TypeLits.Extra`

Fixes some of the issues in #15
---
 CHANGELOG.md              | 3 +++
 ghc-typelits-extra.cabal  | 6 +++---
 src/GHC/TypeLits/Extra.hs | 8 ++++----
 3 files changed, 10 insertions(+), 7 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 387dd68..0c5a2d4 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,8 @@
 # Changelog for the [`ghc-typelits-extra`](http://hackage.haskell.org/package/ghc-typelits-extra) package
 
+# 0.3 *September 14th 2018*
+* Move `KnownNat2` instances for GHC 8.4's `Div` and `Mod` from `ghc-typelits-extra` to `ghc-typelits-knownnat`
+
 # 0.2.6 *Julty 10th 2018*
 * Add support for GHC-8.6.1-alpha1
 
diff --git a/ghc-typelits-extra.cabal b/ghc-typelits-extra.cabal
index 01c4a0c..2e99550 100644
--- a/ghc-typelits-extra.cabal
+++ b/ghc-typelits-extra.cabal
@@ -1,5 +1,5 @@
 name:                ghc-typelits-extra
-version:             0.2.6
+version:             0.3
 synopsis:            Additional type-level operations on GHC.TypeLits.Nat
 description:
   Additional type-level operations on @GHC.TypeLits.Nat@:
@@ -69,7 +69,7 @@ library
                        ghc                       >= 7.10    && <8.8,
                        ghc-prim                  >= 0.5     && <1.0,
                        ghc-tcplugins-extra       >= 0.2,
-                       ghc-typelits-knownnat     >= 0.5     && <0.6,
+                       ghc-typelits-knownnat     >= 0.6     && <0.7,
                        ghc-typelits-natnormalise >= 0.6     && <0.7,
                        integer-gmp               >= 1.0     && <1.1,
                        transformers              >= 0.4.2.0 && <0.6
@@ -98,7 +98,7 @@ test-suite test-ghc-typelits-extra
   Other-Modules:       ErrorTests
   build-depends:       base                      >= 4.8 && <5,
                        ghc-typelits-extra,
-                       ghc-typelits-knownnat     >= 0.2,
+                       ghc-typelits-knownnat     >= 0.6,
                        ghc-typelits-natnormalise >= 0.4.1,
                        tasty                     >= 0.10,
                        tasty-hunit               >= 0.9,
diff --git a/src/GHC/TypeLits/Extra.hs b/src/GHC/TypeLits/Extra.hs
index 567aaf0..f28ae2d 100644
--- a/src/GHC/TypeLits/Extra.hs
+++ b/src/GHC/TypeLits/Extra.hs
@@ -129,14 +129,14 @@ instance (KnownNat x, KnownNat y) => KnownNat2 $(nameToSymbol ''Min) x y where
 -- "GHC.TypeLits.Extra.Solver".
 type family Div (x :: Nat) (y :: Nat) :: Nat where
   Div x 1 = x
+
+instance (KnownNat x, KnownNat y, 1 <= y) => KnownNat2 $(nameToSymbol ''Div) x y where
+  natSing2 = SNatKn (quot (N.natVal (Proxy @x)) (N.natVal (Proxy @y)))
 #endif
 
 -- | A variant of 'Div' that rounds up instead of down
 type DivRU n d = Div (n + (d - 1)) d
 
-instance (KnownNat x, KnownNat y, 1 <= y) => KnownNat2 $(nameToSymbol ''Div) x y where
-  natSing2 = SNatKn (quot (N.natVal (Proxy @x)) (N.natVal (Proxy @y)))
-
 #if !MIN_VERSION_ghc(8,4,0)
 -- | Type-level 'mod'
 --
@@ -144,10 +144,10 @@ instance (KnownNat x, KnownNat y, 1 <= y) => KnownNat2 $(nameToSymbol ''Div) x y
 -- "GHC.TypeLits.Extra.Solver".
 type family Mod (x :: Nat) (y :: Nat) :: Nat where
   Mod x 1 = 0
-#endif
 
 instance (KnownNat x, KnownNat y, 1 <= y) => KnownNat2 $(nameToSymbol ''Mod) x y where
   natSing2 = SNatKn (rem (N.natVal (Proxy @x)) (N.natVal (Proxy @y)))
+#endif
 
 -- | Type-level `divMod`
 type DivMod n d = '(Div n d, Mod n d)