Run ghcid in a monorepo via stack

stack-ghcid.sh

project=$(basename "$(pwd)")

# build dependencies
build_deps="stack build $project --fast --pedantic --dependencies-only --interleaved-output"

# restart on changes in other packages
restarts=$(find ../. -maxdepth 1 -type d \
  -not -name "$project" \
  -not -name .stack-work \
  -not -name . \
  -printf '--restart %s ')

# define expression for testing
if [ -z "$1" ]; then
  test_expression="main"
else
  test_expression="Test.Hspec.hspec $1.spec"
fi

# define ghci execution command
execute_options="--interleaved-output --ghci-options '-fobject-code +RTS -N'"
execute="stack ghci $project\:lib $project\:spec $execute_options"

stack exec -- ghcid \
  --command "$build_deps;$execute" \
  --test "$test_expression" \
  --restart package.yaml \
  $restarts

Credit to @5outh for starting the ball rolling with basename and $1.spec.