Data.Machine.Plan

A Plan k o a is a specification for a pure Machine, that reads inputs selected by k with types based on i, writes values of type o, and has intermediate results of type a.

A Plan k o a can be used as a PlanT k o m a for any Monad m.

It is perhaps easier to think of Plan in its un-cps'ed form, which would look like:

data Plan k o a
  = Done a
  | Yield o (Plan k o a)
  | forall z. Await (z -> Plan k o a) (k z) (Plan k o a)
  | Fail

Deconstruct a Plan without reference to a Monad.

You can construct a Plan (or PlanT), turning it into a Machine (or MachineT).

Output a result.

Like yield, except stops if there is no value to yield.

Wait for input.

await = awaits id

Wait for a particular input.

awaits L  :: Plan (T a b) o a
awaits R  :: Plan (T a b) o b
awaits id :: Plan (Is i) o i

Run a monadic action repeatedly yielding its results, until it returns Nothing.