- Sam Lindley AND Conor McBride AND Craig McLaughlin
based on Plotkin and Power’s algebraic effects
- and Plotkin and Pretnar’s handlers for algebraic effects
operators generalize functions and effects
- pure function is an operator with no effects
- what bidirectional effect type system means?
- what is effect polymorphism?
works in strict language (but with possibly delayed computations)
- “The absence of explicit plumbing in Frank depends crucially on the fact that Frank, unlike Haskell, has a fixed evaluation order.”
handling effects is just a function
state : S -> <State S>X -> X state _ x = x -- this catch-all does not include effects---only values state s <get -> k> = state s (k s) state _ <put s -> k> = state s (k unit)
handling multiple effects
pipe : <Send X>Unit -> <Receive X>Y -> [Abort]Y pipe <send x -> s> <receive -> r> = pipe (s unit) (r x) pipe <_> y = y pipe unit <_> = abort!