to run:
Using Atom, in a terminal run
cd app
stack exec glance-exe -- -l -s Main.hs -o ../output.svg

or if that does not work

stack build  --exec "glance-exe -o output.svg -w 500"

View circle.svg with svg-preview plug-in.

To use ghci with the test file:
stack ghci glance:test:glance-test

For all warnings (some warnings duplicated):
stack clean
stack build --test --no-run-tests --ghc-options -Wall

To open documentation for other libraries:
stack haddock --open <package-name>