Skuld.Comp.ITotalLinearHandler behaviour (skuld v0.28.0)

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Behaviour for effect operation handlers that are provably total and linear.

A handler is total if it produces a value for every possible input — it never diverges, never throws an exception, and never raises an effect. A handler is linear if it has use-once semantics — the handler always either returns normally or the computation ends.

When both properties hold, the comp macro can emit an optimised call path that skips continuation allocation and CPS indirection:

{value, env2} = handler.(args, env)
comp2 = f.(value)
call(comp2, env2, k)

Example

defmodule MyTotalLinearEffect do
  @behaviour Skuld.Comp.ITotalLinearHandler

  @total [:get]
  @linear [:get]

  @impl Skuld.Comp.ITotalLinearHandler
  def handle(:get, env) do
    {Env.get_state!(env, @key), env}
  end
end

See Also

Summary

Callbacks

handle(args, env)

Callbacks

handle(args, env)

@callback handle(args :: term(), env :: Skuld.Comp.Types.env()) ::
  {Skuld.Comp.Types.result(), Skuld.Comp.Types.env()}