Demonstrate incompatibility of Haskell packages cryptonite and blake2

script.sh

#!/bin/bash

# The Haskell packages cryptonite and blake2 both include a version
# of the C sources of the blake2 reference implementation. Linking
# both packages into the same Haskell binary can result in a broken
# binary that produces unsound results.

TDIR=$(mktemp -d "${TMPDIR:-/tmp/}$(basename $0).XXXXXXXXXXXX")
trap "{ rm -rf "$TDIR"; }" EXIT

HSFILE="$TDIR/Main.hs"
MAIN="$TDIR/main"

cat > "$HSFILE" << EOF
{-# LANGUAGE OverloadedStrings #-}
module Main where
import Crypto.Hash.BLAKE2.BLAKE2b
main = print $ hash 64 mempty "abc"
EOF

# compile Main.hs

ghc "$HSFILE" -o "$MAIN"
rm -f "$MAIN"

# from here on only linking happens

function get-id { ghc-pkg field $1 id | cut -d ' ' -f 2 ; }

echo
ghc "$HSFILE" -o "$MAIN"
echo ghc ./Tmp.hs -o "$MAIN"
"$MAIN"
rm -f "$MAIN"

echo
ghc -package-id `get-id blake2` "$HSFILE" -o "$MAIN"
echo ghc -package-id `get-id blake2` "$HSFILE" -o "$MAIN"
"$MAIN"
rm -f "$MAIN"

echo
ghc -package-id `get-id cryptonite` "$HSFILE" -o "$MAIN"
echo ghc -package-id `get-id cryptonite` "$HSFILE" -o "$MAIN"
"$MAIN"
rm -f "$MAIN"

echo
ghc -package-id `get-id blake2` -package-id `get-id cryptonite` "$HSFILE" -o "$MAIN"
echo ghc -package-id `get-id blake2` -package-id `get-id cryptonite` "$HSFILE" -o "$MAIN"
"$MAIN"
rm -f "$MAIN"