traversal_loop.bend source

traversal_loop.bend on the hub · documented module

# One sequential traversal for affine runtime owners and reusable proof states.# The step is a compile-time template: no closure allocation in the loop.import Basedef run(~State: Type,~step: State -> State,count: Nat,state: State) -> State:  match count:    case 0n: state    case 1n+rest: run(~State,~step,rest,step(state))# The same loop handing its final state to finish in the base case. A caller# that stores its accumulators in finish keeps them out of the loop's return# value, so an outlined loop never passes accumulators back by value.def run_then(~State: Type,~Result: Type,~step: State -> State,~finish: State -> Result,count: Nat,state: State) -> Result:  match count:    case 0n: finish(state)    case 1n+rest: run_then(~State,~Result,~step,~finish,rest,step(state))