Clean up code

package.yaml

@@ -42,6 +42,7 @@ library:
   - array
   - base64-bytestring
   - hexstring
+  - blake2
 
 executables:
   zenith:

src/Zenith.hs

@@ -7,9 +7,11 @@ module Zenith where
 
 import Control.Concurrent (threadDelay)
 import Control.Monad
+import Crypto.Hash.BLAKE2.BLAKE2b
 import Data.Aeson
 import Data.Aeson.Types
 import qualified Data.Array as A
+import Data.Bits
 import qualified Data.ByteString as B
 import qualified Data.ByteString.Base64 as B64
 import qualified Data.ByteString.Char8 as C

stack.yaml

@@ -17,7 +17,7 @@
 #
 # resolver: ./custom-snapshot.yaml
 # resolver: https://example.com/snapshots/2018-01-01.yaml
-resolver: lts-20.8
+resolver: lts-20.16
 
 # User packages to be built.
 # Various formats can be used as shown in the example below.

stack.yaml.lock

@@ -17,7 +17,7 @@ packages:
     git: https://github.com/reach-sh/haskell-hexstring.git
 snapshots:
 - completed:
-    sha256: bfafe5735ccb74527d754b1f9999ded72d7c3a6c3a88529449661431ccfbd6cc
-    size: 649327
-    url: https://raw.githubusercontent.com/commercialhaskell/stackage-snapshots/master/lts/20/8.yaml
-  original: lts-20.8
+    sha256: dad15e2ec0c09280a5c2e07190fb18710fc54472f029f34f861f686540824d81
+    size: 649592
+    url: https://raw.githubusercontent.com/commercialhaskell/stackage-snapshots/master/lts/20/16.yaml
+  original: lts-20.16

zenith.cabal

@@ -1,6 +1,6 @@
 cabal-version: 1.12
 
--- This file has been generated from package.yaml by hpack version 0.35.0.
+-- This file has been generated from package.yaml by hpack version 0.35.1.
 --
 -- see: https://github.com/sol/hpack
 
@@ -36,6 +36,7 @@ library
     , array
     , base >=4.7 && <5
     , base64-bytestring
+    , blake2
     , bytestring
     , haskoin-core
     , hexstring