diff options
Diffstat (limited to 'compiler/GHC/Tc/Instance/Class.hs')
| -rw-r--r-- | compiler/GHC/Tc/Instance/Class.hs | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/compiler/GHC/Tc/Instance/Class.hs b/compiler/GHC/Tc/Instance/Class.hs index 43c2092c70..aec5c85e20 100644 --- a/compiler/GHC/Tc/Instance/Class.hs +++ b/compiler/GHC/Tc/Instance/Class.hs @@ -259,12 +259,12 @@ Note [KnownNat & KnownSymbol and EvLit] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ A part of the type-level literals implementation are the classes "KnownNat" and "KnownSymbol", which provide a "smart" constructor for -defining singleton values. Here is the key stuff from GHC.TypeLits +defining singleton values. Here is the key stuff from GHC.TypeNats class KnownNat (n :: Nat) where natSing :: SNat n - newtype SNat (n :: Nat) = SNat Integer + newtype SNat (n :: Nat) = SNat Natural Conceptually, this class has infinitely many instances: @@ -291,10 +291,10 @@ Also note that `natSing` and `SNat` are never actually exposed from the library---they are just an implementation detail. Instead, users see a more convenient function, defined in terms of `natSing`: - natVal :: KnownNat n => proxy n -> Integer + natVal :: KnownNat n => proxy n -> Natural The reason we don't use this directly in the class is that it is simpler -and more efficient to pass around an integer rather than an entire function, +and more efficient to pass around a Natural rather than an entire function, especially when the `KnowNat` evidence is packaged up in an existential. The story for kind `Symbol` is analogous: |