+100 I first heard of this in the great Functional Core, Imperative Shell [1] screencast of Destroy All Software. It allows you to easily unit test your functi

+100 I first heard of this in the great Functional Core, Imperative Shell [1] screencast of Destroy All Software. It allows you to easily unit test your functional core (as they're just pure functions). [1] https://www.destroyallsoftware.com/screencasts/catalog/functional-core-imperative-shell https://www.destroyallsoftware.com/screencasts/catalog/funct...