From 9db210f5109e8ad3c119224a0cd78d8b0ff4d104 Mon Sep 17 00:00:00 2001
From: Tom Ellis <tom-git@jaguarpaw.co.uk>
Date: Sun, 8 Sep 2024 18:11:17 +0100
Subject: [PATCH] Some docs

---
 .../src/Bluefin/Internal/Effectful.hs         | 168 +++++++++++-------
 1 file changed, 102 insertions(+), 66 deletions(-)

diff --git a/bluefin-internal/src/Bluefin/Internal/Effectful.hs b/bluefin-internal/src/Bluefin/Internal/Effectful.hs
index 20a7bc3..b46d244 100644
--- a/bluefin-internal/src/Bluefin/Internal/Effectful.hs
+++ b/bluefin-internal/src/Bluefin/Internal/Effectful.hs
@@ -12,66 +12,28 @@ import Effectful.Internal.Env
 import qualified Effectful.Internal.Monad as Effectful
 import qualified Effectful.State.Dynamic as St
 
-newtype Effectful es (e :: Effects) = MkEffectful (Env es)
+-- * Bluefin handle
 
-data Bluefin es m a
+-- | Provide access to Effectful operations in Bluefin
+newtype Effectful (es' :: [EffectfulEffect]) (e :: Effects)
+  = MkEffectful (Env es')
 
-type instance DispatchOf (Bluefin es) = Dynamic
+-- * Effectful effect
 
-voidBluefin :: Bluefin es m a -> r
-voidBluefin = \case {}
+-- | Provide access to Bluefin operations in Effectful
+data Bluefin es m a
 
-useEffectful ::
-  (e :> es) =>
-  -- | Bluefin handle to @effectful@ operations
-  Effectful effes e ->
-  -- | An @effectful@ operation
-  Effectful.Eff effes r ->
-  Eff es r
-useEffectful e k =
-  fromEffectful (\Proxy -> Effectful.inject k) e
+-- * Type synonyms
 
-useBluefin ::
-  forall es effes r.
-  (Bluefin es Effectful.:> effes) =>
-  Eff es r ->
-  Effectful.Eff effes r
-useBluefin m =
-  toEffectful (\(_ :: Effectful effes e) -> useImpl @es @(e :& es) m)
+type instance DispatchOf (Bluefin es) = Dynamic
 
-toEffectful ::
-  forall es effes a.
-  (Bluefin es Effectful.:> effes) =>
-  (forall e. Effectful effes e -> Eff (e :& es) a) ->
-  Effectful.Eff effes a
-toEffectful = unsafeToEffectful
+type EffectfulEff = Effectful.Eff
 
-unsafeInterpretBluefin ::
-  Effectful.Eff (Bluefin es : effes) a -> Effectful.Eff effes a
-unsafeInterpretBluefin = Effectful.interpret (\_ -> voidBluefin)
+type EffectfulEffect = Effectful.Effect
 
-fromEffectful ::
-  (e :> es) =>
-  (Proxy es -> Effectful.Eff (Bluefin es : effes) r) ->
-  Effectful effes e ->
-  Eff es r
-fromEffectful m (MkEffectful env) =
-  UnsafeMkEff (Effectful.unEff (unsafeInterpretBluefin (m Proxy)) env)
+type a ::> b = a Effectful.:> b
 
-unsafeToEffectful :: (Effectful es e -> Eff es' a) -> Effectful.Eff es a
-unsafeToEffectful m =
-  Effectful.unsafeEff (\env' -> unsafeUnEff (m (MkEffectful env')))
-
-handleWith ::
-  (e1 :> es) =>
-  -- | An @effectful@ handler
-  (Effectful.Eff (effe : effes) r1 -> Effectful.Eff effes r2) ->
-  -- | An @effectful@ operation, in Bluefin style
-  (forall e. Effectful (effe : effes) e -> Eff (e :& es) r1) ->
-  Effectful effes e1 ->
-  Eff es r2
-handleWith handler m (MkEffectful env) =
-  UnsafeMkEff (Effectful.unEff (handler (unsafeToEffectful m)) env)
+-- * Bluefin handlers
 
 runEffectful ::
   (e1 :> es) =>
@@ -87,26 +49,86 @@ runPureEffectful ::
   Eff es r
 runPureEffectful k = pure (Effectful.runPureEff (unsafeToEffectful k))
 
+handleWith ::
+  (e1 :> es) =>
+  -- | An @effectful@ handler
+  (EffectfulEff (e' : es') r1 -> EffectfulEff es' r2) ->
+  -- | An @effectful@ operation, in Bluefin style
+  (forall e. Effectful (e' : es') e -> Eff (e :& es) r1) ->
+  Effectful es' e1 ->
+  -- | The result of handling the @effectful@ operation in Bluefin
+  -- style using the @effectful@ handler
+  Eff es r2
+handleWith handler m (MkEffectful env) =
+  UnsafeMkEff (Effectful.unEff (handler (unsafeToEffectful m)) env)
+
+-- * Effectful handlers
+
 runBluefin ::
-  Effectful.IOE Effectful.:> effes =>
-  (forall e es. IOE e -> Effectful.Eff (Bluefin (e :& es) : effes) r) ->
-  Effectful.Eff effes r
+  (Effectful.IOE ::> es') =>
+  -- | A Bluefin operation, in Effectful style (with IO)
+  (forall e es. IOE e -> EffectfulEff (Bluefin (e :& es) : es') r) ->
+  EffectfulEff es' r
 runBluefin m = unsafeInterpretBluefin (m MkIOE)
 
 runPureBluefin ::
-  (forall es. Effectful.Eff (Bluefin es : effes) r) ->
-  Effectful.Eff effes r
+  -- | A Bluefin operation, in Effectful style (without IO)
+  (forall es. EffectfulEff (Bluefin es : es') r) ->
+  EffectfulEff es' r
 runPureBluefin = unsafeInterpretBluefin
 
+-- * Use Bluefin operations in @effectful@ and vice versa
+
+useEffectful ::
+  (e :> es) =>
+  -- | Bluefin handle to @effectful@ operations
+  Effectful es' e ->
+  -- | An @effectful@ operation
+  EffectfulEff es' r ->
+  Eff es r
+useEffectful e k =
+  fromEffectful (\Proxy -> Effectful.inject k) e
+
+useBluefin ::
+  forall es es' r.
+  (Bluefin es ::> es') =>
+  Eff es r ->
+  -- | ͘
+  EffectfulEff es' r
+useBluefin m =
+  toEffectful (\(_ :: Effectful es' e) -> useImpl @es @(e :& es) m)
+
+-- * Conversion between @effectful@ and Bluefin
+
+toEffectful ::
+  forall (es :: Effects) (es' :: [EffectfulEffect]) a.
+  (Bluefin es ::> es') =>
+  (forall e. Effectful es' e -> Eff (e :& es) a) ->
+  -- | ͘
+  EffectfulEff es' a
+toEffectful = unsafeToEffectful
+
+fromEffectful ::
+  (e :> es) =>
+  (Proxy es -> EffectfulEff (Bluefin es : es') r) ->
+  Effectful es' e ->
+  -- | ͘
+  Eff es r
+fromEffectful m (MkEffectful env) =
+  UnsafeMkEff (Effectful.unEff (unsafeInterpretBluefin (m Proxy)) env)
+
+-- * Example code
+
 example ::
-  ( St.State Int Effectful.:> es,
-    Er.Error String Effectful.:> es,
-    Bluefin bes Effectful.:> es,
-    e :> bes
+  ( St.State Int ::> es',
+    Er.Error String ::> es',
+    Bluefin es ::> es',
+    e :> es
   ) =>
   State Int e ->
-  Proxy bes ->
-  Effectful.Eff es Int
+  Proxy es ->
+  -- | ͘
+  EffectfulEff es' Int
 example bst (_ :: Proxy bes) = do
   r <- St.get
   St.put (r + 1 :: Int)
@@ -116,14 +138,15 @@ example bst (_ :: Proxy bes) = do
   St.get
 
 bfExample ::
-  forall e es e1 effes.
+  forall e es e1 es'.
   ( e :> es,
     e1 :> es,
-    St.State Int Effectful.:> effes,
-    Er.Error String Effectful.:> effes
+    St.State Int ::> es',
+    Er.Error String ::> es'
   ) =>
   State Int e1 ->
-  Effectful effes e ->
+  Effectful es' e ->
+  -- | ͘
   Eff es Int
 bfExample s e = do
   r <- fromEffectful (\_ -> example s (Proxy @es)) e
@@ -146,3 +169,16 @@ runExample i =
 -- Right 10
 -- > runExample 10
 -- Left "foo"
+
+-- * Unsafe internals
+
+voidBluefin :: Bluefin es m a -> r
+voidBluefin = \case {}
+
+unsafeInterpretBluefin ::
+  EffectfulEff (Bluefin es : es') a -> EffectfulEff es' a
+unsafeInterpretBluefin = Effectful.interpret (\_ -> voidBluefin)
+
+unsafeToEffectful :: (Effectful es e -> Eff es' a) -> EffectfulEff es a
+unsafeToEffectful m =
+  Effectful.unsafeEff (\env' -> unsafeUnEff (m (MkEffectful env')))