From 5565d0bbfb1fbe29258b90dd8bf10c69078cba10 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ole=20Kr=C3=BCger?= <ole@vprsm.de>
Date: Thu, 4 Nov 2021 20:52:49 +0000
Subject: [PATCH] Allow construction of hashes using their underlying
 representation

---
 Data/Digest/Murmur32.hs | 6 +++++-
 Data/Digest/Murmur64.hs | 6 +++++-
 changelog.md            | 5 +++++
 3 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/Data/Digest/Murmur32.hs b/Data/Digest/Murmur32.hs
index 8ea3cd7..239c221 100644
--- a/Data/Digest/Murmur32.hs
+++ b/Data/Digest/Murmur32.hs
@@ -13,7 +13,7 @@ MurmurHash2 algorithm.  See <http://murmurhash.googlepages.com> for
 details on MurmurHash2.
 -}
 module Data.Digest.Murmur32
-  ( Hash32, asWord32,
+  ( Hash32, asWord32, asHash32,
     Hashable32(..),
     hash32AddWord32, hash32AddInt, hash32, hash32WithSeed
   )
@@ -39,6 +39,10 @@ instance Show Hash32 where
 asWord32 :: Hash32 -> Word32
 asWord32 (Hash32 w) = w
 
+-- | Coerce a 32 bit word into a hash. This does not hash the input.
+asHash32 :: Word32 -> Hash32
+asHash32 = Hash32
+
 class Hashable32 a where
   hash32Add :: a -> Hash32 -> Hash32
 
diff --git a/Data/Digest/Murmur64.hs b/Data/Digest/Murmur64.hs
index 6fcb6d4..6128373 100644
--- a/Data/Digest/Murmur64.hs
+++ b/Data/Digest/Murmur64.hs
@@ -13,7 +13,7 @@ MurmurHash2 algorithm.  See <http://murmurhash.googlepages.com> for
 details on MurmurHash2.
 -}
 module Data.Digest.Murmur64
-  ( Hash64, asWord64,
+  ( Hash64, asWord64, asHash64,
     Hashable64(..),
     hash64AddWord64, hash64AddInt, hash64, hash64WithSeed, combine,
   )
@@ -39,6 +39,10 @@ instance Show Hash64 where
 asWord64 :: Hash64 -> Word64
 asWord64 (Hash64 w) = w
 
+-- | Coerce a 64 bit word into a hash. This does not hash the input.
+asHash64 :: Word64 -> Hash64
+asHash64 = Hash64
+
 class Hashable64 a where
   hash64Add :: a -> Hash64 -> Hash64
 
diff --git a/changelog.md b/changelog.md
index 1092f61..6926c06 100644
--- a/changelog.md
+++ b/changelog.md
@@ -1,3 +1,8 @@
+### Unreleased
+
+  - Introduce `asHash64` and `asHash32` which allow construction of `Hash64`
+    and `Hash32` respectively from their underlying word representation.
+
 ### 0.1.0.10
 
   - Replace use of deprecated `bitSize` by `finiteBitSize`