scalastyle and scalariform setup
ex. 6.7: bug fixed + formatting
ex. 6.7: sequence as foldRight (initial plan) - comment out output test
ex. 6.7: ints via sequence (wow!)
ex. 6.7: ints via sequence (wow!) - val rename
ex. 6.7: flatMap (no tests)
ex. 6.8: flatMap + 1st version of nonNegativeLessThan
ex. 6.8: simplify using unit
ex. 6.8: implementation according to spec (contrived?)
remove output from test
ex. 6.9: map, map2 in terms of flatMap
ex. 6.9: alternate map2 in terms of map (in terms of flatMap) and flatMap - commented out