ImplicitParams don't work well

[tomjaguarpaw]

We might like to pass Bluefin handles as ImplicitParams, but it doesn't work well, because of the same incoherent instance type inference issues as in #21.

Here's a demonstration of the best I have been able to achieve so far:

bluefin/bluefin-internal/src/Bluefin/Internal/Examples.hs

Lines 1098 to 1152 in 783da15

	-- welltypedwitch raised the intriguing possibility of using
	-- ImplicitParams to avoid having to pass effect handles explicitly.
	-- Unfortunately I've been snagged on two issues:
	--
	-- 1. It doesn't seem possible to bind an implicit parameter in a
	-- lambda. (See
	-- https://discourse.haskell.org/t/why-cant-an-implicitparam-be-bound-by-a-lambda/8936/2)
	--
	-- 2. Type inference gets stuck, because of the difficulty resolving
	-- incoherent instances, the same as in
	--
	-- <https://github.com/tomjaguarpaw/bluefin/issues/21>
	-- We might want to resolve 1 by putting the ImplicitParam as an
	-- argument to the handler.
	evalStateI ::
	-- | Initial state
	s ->
	-- | Stateful computation
	(forall st. (?st :: State s st) => Eff (st :& es) a) ->
	-- | Result
	Eff es a
	evalStateI s f = evalState s (\x -> let ?st = x in f)
	runEffI :: (forall es. (?io :: IOE es) => Eff es r) -> IO r
	runEffI f = runEff (\io -> let ?io = io in pushFirst f)
	countExampleImpl ::
	forall e e1 es.
	(?st :: State Int e1, e1 :> es) =>
	(?io :: IOE e, e :> es) =>
	Eff es ()
	countExampleImpl = do
	withJump $ \break -> forever $ do
	n <- getI
	when (n >= 10) (jumpTo break)
	effIOI (print n)
	modifyI (+ 1)
	countExampleI :: IO ()
	countExampleI = runEffI $ do
	evalStateI @Int 0 $ do
	countExampleImpl
	-- When we try to use an effect bound in a local handler we get stuck.
	-- We have to annotate the type.
	countExampleI2 :: IO ()
	countExampleI2 = runEffI $ do
	evalStateI @Int 0 $ do
	withJump $ \break -> forever $ do
	_ :: State Int st <- pure ?st
	n <- getI @st
	when (n >= 10) (jumpTo break)
	effIOI (print n)
	modifyI @st (+ 1)