From 32cbe41fbecdd84bacf62813eff2b83ff5550942 Mon Sep 17 00:00:00 2001
From: Duncan Coutts <duncan@well-typed.com>
Date: Fri, 27 Dec 2019 17:23:39 +0100
Subject: [PATCH] Add and use compactTxOut{Address,Value} projections

For when we want just one component of the CompactTxOut without
uncompacting the other (e.g. computing the utxo balance).
---
 cardano-ledger/src/Cardano/Chain/UTxO/Compact.hs | 10 ++++++++++
 cardano-ledger/src/Cardano/Chain/UTxO/UTxO.hs    |  4 +---
 2 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/cardano-ledger/src/Cardano/Chain/UTxO/Compact.hs b/cardano-ledger/src/Cardano/Chain/UTxO/Compact.hs
index 1df96fc1..d427b50c 100644
--- a/cardano-ledger/src/Cardano/Chain/UTxO/Compact.hs
+++ b/cardano-ledger/src/Cardano/Chain/UTxO/Compact.hs
@@ -28,6 +28,8 @@ module Cardano.Chain.UTxO.Compact
   , CompactTxOut(..)
   , toCompactTxOut
   , fromCompactTxOut
+  , compactTxOutAddress
+  , compactTxOutValue
   )
 where
 
@@ -41,6 +43,7 @@ import qualified Data.ByteArray as BA (convert)
 import qualified Data.ByteString.Lazy as BSL (fromStrict, toStrict)
 
 import Cardano.Binary (FromCBOR(..), ToCBOR(..), encodeListLen, enforceSize)
+import Cardano.Chain.Common (Address)
 import Cardano.Chain.Common.Compact
   (CompactAddress, fromCompactAddress, toCompactAddress)
 import Cardano.Chain.Common.Lovelace
@@ -259,3 +262,10 @@ toCompactLovelace = CompactLovelace . fromIntegral . lovelaceToNatural
 
 fromCompactLovelace :: CompactLovelace -> Lovelace
 fromCompactLovelace (CompactLovelace n) = naturalToLovelace (fromIntegral n)
+
+compactTxOutAddress :: CompactTxOut -> Address
+compactTxOutAddress (CompactTxOut addr _) = fromCompactAddress addr
+
+compactTxOutValue :: CompactTxOut -> Lovelace
+compactTxOutValue (CompactTxOut _ lovelace) = fromCompactLovelace lovelace
+
diff --git a/cardano-ledger/src/Cardano/Chain/UTxO/UTxO.hs b/cardano-ledger/src/Cardano/Chain/UTxO/UTxO.hs
index 57201cdb..09777b2d 100644
--- a/cardano-ledger/src/Cardano/Chain/UTxO/UTxO.hs
+++ b/cardano-ledger/src/Cardano/Chain/UTxO/UTxO.hs
@@ -55,6 +55,7 @@ import Cardano.Chain.UTxO.Compact
   , fromCompactTxOut
   , toCompactTxIn
   , toCompactTxOut
+  , compactTxOutValue
   )
 import Cardano.Crypto (hash)
 
@@ -137,9 +138,6 @@ concat = foldM union empty
 
 balance :: UTxO -> Lovelace
 balance = foldMap compactTxOutValue . unUTxO
- where
-  compactTxOutValue :: CompactTxOut -> Lovelace
-  compactTxOutValue = txOutValue . fromCompactTxOut
 
 (<|) :: Set TxIn -> UTxO -> UTxO
 (<|) inputs = UTxO . flip M.restrictKeys compactInputs . unUTxO