From 7ece827d45a3025c7a5a629918f7a10ce35120b9 Mon Sep 17 00:00:00 2001
From: Johannes Lund <johannes.lund@iohk.io>
Date: Tue, 7 May 2019 11:57:42 +0200
Subject: [PATCH 1/3] Rewrite Quantity documentation

---
 lib/core/src/Data/Quantity.hs | 24 +++++++++++++++++++-----
 1 file changed, 19 insertions(+), 5 deletions(-)

diff --git a/lib/core/src/Data/Quantity.hs b/lib/core/src/Data/Quantity.hs
index f246c9f81fe..83b7fa344db 100644
--- a/lib/core/src/Data/Quantity.hs
+++ b/lib/core/src/Data/Quantity.hs
@@ -52,18 +52,32 @@ import GHC.TypeLits
 import qualified Data.Text as T
 
 
--- | Represents a value that has an associated unit of measure, based on some
---   underlying type.
+-- | @Quantity (u :: Symbol) a@ is a primitive @a@  multiplied by an unit @u@.
 --
--- >>> newtype Amount = Amount (Quantity "lovelace" Word32)
+-- Example:
+--
+-- Instead of providing the unit implicitly as a comment, or a part of a name
+--
+-- >>> a :: Word32 -- in lovelace
+--
+-- we can write
+--
+-- >>> a :: Quantity "lovelace" Word32
+--
+-- which now has a different type from
+--
+-- >>> b :: Quantity "lovelace/byte" Word32
+--
+-- so mixing them up is more difficult.
+--
+-- The unit is mostly a phantom type, but it is also included in the
+-- @ToJSON@/@FromJSON@ instances.
 newtype Quantity (u :: Symbol) a = Quantity a
     deriving stock (Generic, Show, Eq, Ord)
     deriving newtype (Bounded, Enum)
 
 instance NFData a => NFData (Quantity u a)
 
--- | Encode to JSON delegating the
---
 -- >>> Aeson.encode $ Quantity @"lovelace" 14
 -- {"unit":"lovelace","quantity":14}
 instance (KnownSymbol u, ToJSON a) => ToJSON (Quantity u a) where

From b870798a72c5518e4f82659996d3a2b0489c6959 Mon Sep 17 00:00:00 2001
From: Johannes Lund <johannes.lund@iohk.io>
Date: Tue, 7 May 2019 12:08:54 +0200
Subject: [PATCH 2/3] Rename `u` to `unit`

---
 lib/core/src/Data/Quantity.hs | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/lib/core/src/Data/Quantity.hs b/lib/core/src/Data/Quantity.hs
index 83b7fa344db..79de53091c9 100644
--- a/lib/core/src/Data/Quantity.hs
+++ b/lib/core/src/Data/Quantity.hs
@@ -52,7 +52,7 @@ import GHC.TypeLits
 import qualified Data.Text as T
 
 
--- | @Quantity (u :: Symbol) a@ is a primitive @a@  multiplied by an unit @u@.
+-- | @Quantity (unit :: Symbol) a@ is a primitive @a@  multiplied by an @unit@.
 --
 -- Example:
 --
@@ -72,26 +72,26 @@ import qualified Data.Text as T
 --
 -- The unit is mostly a phantom type, but it is also included in the
 -- @ToJSON@/@FromJSON@ instances.
-newtype Quantity (u :: Symbol) a = Quantity a
+newtype Quantity (unit :: Symbol) a = Quantity a
     deriving stock (Generic, Show, Eq, Ord)
     deriving newtype (Bounded, Enum)
 
-instance NFData a => NFData (Quantity u a)
+instance NFData a => NFData (Quantity unit a)
 
 -- >>> Aeson.encode $ Quantity @"lovelace" 14
 -- {"unit":"lovelace","quantity":14}
-instance (KnownSymbol u, ToJSON a) => ToJSON (Quantity u a) where
+instance (KnownSymbol unit, ToJSON a) => ToJSON (Quantity unit a) where
     toJSON (Quantity a) = object
-        [ "unit"     .= symbolVal (Proxy :: Proxy u)
+        [ "unit"     .= symbolVal (Proxy :: Proxy unit)
         , "quantity" .= toJSON a
         ]
 
-instance (KnownSymbol u, FromJSON a) => FromJSON (Quantity u a) where
+instance (KnownSymbol unit, FromJSON a) => FromJSON (Quantity unit a) where
     parseJSON = withObject "Quantity" $ \o -> do
-        verifyUnit (Proxy :: Proxy u) =<< o .: "unit"
+        verifyUnit (Proxy :: Proxy unit) =<< o .: "unit"
         Quantity <$> o .: "quantity"
       where
-        verifyUnit :: Proxy (u :: Symbol) -> Value -> Parser ()
+        verifyUnit :: Proxy (unit :: Symbol) -> Value -> Parser ()
         verifyUnit proxy = \case
             String u' | u' == T.pack u -> pure ()
             _ -> fail $

From 2390a8d58e02b4462157187d3d94dcb2828b3048 Mon Sep 17 00:00:00 2001
From: Johannes Lund <johannes.lund@iohk.io>
Date: Tue, 7 May 2019 12:27:36 +0200
Subject: [PATCH 3/3] Move ToJSON comment

---
 lib/core/src/Data/Quantity.hs | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/lib/core/src/Data/Quantity.hs b/lib/core/src/Data/Quantity.hs
index 79de53091c9..46242635f6f 100644
--- a/lib/core/src/Data/Quantity.hs
+++ b/lib/core/src/Data/Quantity.hs
@@ -72,14 +72,15 @@ import qualified Data.Text as T
 --
 -- The unit is mostly a phantom type, but it is also included in the
 -- @ToJSON@/@FromJSON@ instances.
+--
+-- >>> Aeson.encode $ Quantity @"lovelace" 14
+-- {"unit":"lovelace","quantity":14}
 newtype Quantity (unit :: Symbol) a = Quantity a
     deriving stock (Generic, Show, Eq, Ord)
     deriving newtype (Bounded, Enum)
 
 instance NFData a => NFData (Quantity unit a)
 
--- >>> Aeson.encode $ Quantity @"lovelace" 14
--- {"unit":"lovelace","quantity":14}
 instance (KnownSymbol unit, ToJSON a) => ToJSON (Quantity unit a) where
     toJSON (Quantity a) = object
         [ "unit"     .= symbolVal (Proxy :: Proxy unit)