diff --git a/CHANGELOG.md b/CHANGELOG.md
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--- /dev/null
+++ b/CHANGELOG.md
@@ -0,0 +1,4 @@
+# Change log
+
+Heptapod follows the [Package Versioning Policy](https://pvp.haskell.org).
+You can find release notes [on GitHub](https://github.com/tfausak/heptapod/releases).
diff --git a/LICENSE.txt b/LICENSE.txt
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--- /dev/null
+++ b/LICENSE.txt
@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2024 Taylor Fausak
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
diff --git a/README.md b/README.md
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+++ b/README.md
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+# Heptapod
+
+Heptapod is a Haskell library for generating version 7 UUIDs.
diff --git a/heptapod.cabal b/heptapod.cabal
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--- /dev/null
+++ b/heptapod.cabal
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+cabal-version: 2.2
+category: Data
+description: Heptapod generates UUIDv7 values.
+extra-doc-files:
+  CHANGELOG.md
+  README.md
+
+license-file: LICENSE.txt
+license: MIT
+maintainer: Taylor Fausak
+name: heptapod
+synopsis: Generate UUIDv7 values.
+version: 0.2024.8.16
+
+source-repository head
+  location: https://github.com/tfausak/heptapod
+  type: git
+
+flag pedantic
+  default: False
+  manual: True
+
+common library
+  build-depends: base ^>=4.18.0.0 || ^>=4.19.0.0 || ^>=4.20.0.0
+  default-language: Haskell2010
+  ghc-options:
+    -Weverything
+    -Wno-implicit-prelude
+    -Wno-missing-export-lists
+    -Wno-missing-safe-haskell-mode
+    -Wno-prepositive-qualified-module
+    -Wno-safe
+    -Wno-unsafe
+
+  if flag(pedantic)
+    ghc-options: -Werror
+
+library
+  import: library
+  build-depends:
+    bytestring ^>=0.11.5.3 || ^>=0.12.1.0,
+    entropy ^>=0.4.1.10,
+    time ^>=1.12.2 || ^>=1.14,
+    uuid-types ^>=1.0.6,
+
+  -- cabal-gild: discover source/library
+  exposed-modules: Heptapod
+  hs-source-dirs: source/library
diff --git a/source/library/Heptapod.hs b/source/library/Heptapod.hs
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+++ b/source/library/Heptapod.hs
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+-- | This module provides functions for building and generating version 7 UUIDs
+-- as defined by section 5.7 of RFC 9562.
+--
+-- <https://datatracker.ietf.org/doc/html/rfc9562#name-uuid-version-7>
+module Heptapod where
+
+import qualified Data.Bits as Bits
+import qualified Data.ByteString as ByteString
+import qualified Data.Int as Int
+import qualified Data.Time.Clock.System as Time
+import qualified Data.UUID.Types as UUID
+import qualified Data.Word as Word
+import qualified System.Entropy as Entropy
+
+-- | Generates a UUIDv7 using the current time (from 'Time.getSystemTime') and
+-- random data (from 'Entropy.getEntropy').
+generate :: IO UUID.UUID
+generate = do
+  t <- Time.getSystemTime
+  -- Note that we only need 74 bits (12 + 62) of randomness. That's a little
+  -- more than 9 bytes (72 bits), so we have to request 10 bytes (80 bits) of
+  -- entropy. The extra 6 bits are discarded.
+  b <- Entropy.getEntropy 10
+  pure $
+    let u8_u64 = fromIntegral :: Word.Word8 -> Word.Word64
+        f = Bits.shift . u8_u64 . ByteString.index b
+        r = f 0 0 + f 1 8
+        s = f 2 0 + f 3 8 + f 4 16 + f 5 24 + f 6 32 + f 7 40 + f 8 48 + f 9 56
+     in build t r s
+
+-- | Builds a UUIDv7 using the provided fields. Typically you will want to use
+-- the 'generate' function instead.
+build ::
+  -- | Corresponds to the @unix_ts_ms@ field.
+  Time.SystemTime ->
+  -- | Corresponds to the @rand_a@ field. Only the low 12 bits are used.
+  Word.Word64 ->
+  -- | Corresponds to the @rand_b@ field. Only the low 62 bits are used.
+  Word.Word64 ->
+  UUID.UUID
+build t r s =
+  let i64_u64 = fromIntegral :: Int.Int64 -> Word.Word64
+      u32_u64 = fromIntegral :: Word.Word32 -> Word.Word64
+      unix_ts_ms =
+        Bits.shift
+          ( (i64_u64 (Time.systemSeconds t) * 1000)
+              + u32_u64 (div (Time.systemNanoseconds t) 1000000)
+          )
+          16
+      ver = Bits.shift 0x7 12 :: Word.Word64
+      rand_a = r Bits..&. 0x0fff
+      var = Bits.shift 0x2 62 :: Word.Word64
+      rand_b = s Bits..&. 0x3fffffffffffffff
+   in UUID.fromWords64 (unix_ts_ms + ver + rand_a) (var + rand_b)