Side effects: Observable effects of a computation other than its return value Algebraic effects: Represent side effects as sets of operations that interact with the context of a computation

we can pause execution and ask the context to execute a get() for use and return the resulting value

By thinking of effects this way we separate the specification of how to execute pure computations from the specification of how side-effects behave

implementation:

• entering an effect handler creates a fresh stack
• these stacks are heap allocated and dynamically resized
• performing an effect wraps the current stack in a continuation and executes the handler on the previous stack
• continuing a continuation reinstances the paused stack and resumes its execution