Strongly separate clash-protocols-base and clash-protocols

`clash-protocols-base` should only contain code and definitions related to the circuit plugin.
This includes the `Circuit` definition and `Protocol` typeclass. Furthermore we include instances
for types imported from underlying clash libraries such as tuples, `Vec` and `Signal`.

clash-protocols-base/clash-protocols-base.cabal

@@ -112,7 +112,7 @@ library
 
   exposed-modules:
     Protocols.Cpp
-    Protocols.Internal
+    Protocols.Circuit
     Protocols.Internal.Classes
     Protocols.Internal.TaggedBundle
     Protocols.Internal.TaggedBundle.TH

clash-protocols-base/src/Protocols/Circuit.hs

@@ -0,0 +1,38 @@
+{-# OPTIONS_GHC -Wno-dodgy-exports #-}
+{-# OPTIONS_GHC -fno-warn-orphans #-}
+
+module Protocols.Circuit (
+  module Protocols.Internal.Classes,
+) where
+
+import Clash.Signal
+import Clash.Sized.Vector
+import GHC.TypeNats (KnownNat)
+import Protocols.Cpp (maxTupleSize)
+import Protocols.Internal.TH
+import Protocols.Internal.Classes
+
+instance Protocol () where
+  type Fwd () = ()
+  type Bwd () = ()
+
+{- | __NB__: The documentation only shows instances up to /3/-tuples. By
+default, instances up to and including /12/-tuples will exist. If the flag
+@large-tuples@ is set instances up to the GHC imposed limit will exist. The
+GHC imposed limit is either 62 or 64 depending on the GHC version.
+-}
+instance Protocol (a, b) where
+  type Fwd (a, b) = (Fwd a, Fwd b)
+  type Bwd (a, b) = (Bwd a, Bwd b)
+
+-- Generate n-tuple instances, where n > 2
+protocolTupleInstances 3 maxTupleSize
+
+instance (KnownNat n) => Protocol (Vec n a) where
+  type Fwd (Vec n a) = Vec n (Fwd a)
+  type Bwd (Vec n a) = Vec n (Bwd a)
+
+-- XXX: Type families with Signals on LHS are currently broken on Clash:
+instance Protocol (CSignal dom a) where
+  type Fwd (CSignal dom a) = Signal dom a
+  type Bwd (CSignal dom a) = Signal dom ()

clash-protocols-base/src/Protocols/Internal/Classes.hs

@@ -5,6 +5,7 @@ for instances. They are defined separately to avoid import loops.
 This module is not exported; the classes and their (orphan) instances are
 exported elsewhere.
 -}
+{-# LANGUAGE RoleAnnotations #-}
 module Protocols.Internal.Classes where
 
 import Clash.Signal
@@ -141,6 +142,16 @@ class (Protocol p) => IdleCircuit p where
   idleFwd :: Proxy p -> Fwd (p :: Type)
   idleBwd :: Proxy p -> Bwd (p :: Type)
 
+{- | Circuit protocol with /Signal dom a/ in its forward direction, and
+/()/ in its backward direction. Convenient for exposing protocol
+internals, or simply for undirectional streams.
+Note: 'CSignal' exists to work around [issue 760](https://github.com/clash-lang/clash-compiler/issues/760)
+      in Clash, where type families with 'Signal' on the LHS are broken.
+-}
+data CSignal (dom :: Domain) (a :: Type)
+
+type role CSignal nominal representational
+
 {- | Force a /nack/ on the backward channel and /no data/ on the forward
 channel if reset is asserted.
 -}

clash-protocols-base/src/Protocols/Plugin.hs

@@ -15,7 +15,7 @@ module Protocols.Plugin (
 import Prelude
 
 -- clash-protocols
-import Protocols.Internal
+import Protocols.Internal.Classes
 import Protocols.Internal.TaggedBundle
 import Protocols.Internal.Units
 import Protocols.Plugin.Internal

clash-protocols-base/src/Protocols/Plugin/Internal.hs

@@ -7,7 +7,22 @@ module Protocols.Plugin.Internal where
 import Clash.Explicit.Prelude
 
 import Data.Tagged
-import Protocols.Internal
+import GHC.Base (Any)
+import Protocols.Internal.Classes
+
+{- | Picked up by "Protocols.Plugin" to process protocol DSL. See
+"Protocols.Plugin" for more information.
+-}
+circuit :: Any
+circuit =
+  error "'protocol' called: did you forget to enable \"Protocols.Plugin\"?"
+
+{- | Picked up by "Protocols.Plugin" to tie circuits together. See
+"Protocols.Plugin" for more information.
+-}
+(-<) :: Any
+(-<) =
+  error "(-<) called: did you forget to enable \"Protocols.Plugin\"?"
 
 {- | Convenience type alias. A circuit where all parts are decorated with a
 tag, referring to the @a@ and @b@ in its main signature. This is (indirectly)

clash-protocols/clash-protocols.cabal

@@ -145,6 +145,7 @@ library
     Protocols.Axi4.WriteData
     Protocols.Axi4.WriteResponse
     Protocols.Df
+    Protocols.Internal
     Protocols.DfConv
     Protocols.Hedgehog
     Protocols.Hedgehog.Internal

clash-protocols-base/src/Protocols/Internal.hs → clash-protocols/src/Protocols/Internal.hs

@@ -26,12 +26,11 @@ import GHC.Base (Any)
 import Prelude hiding (const, map)
 
 import qualified Clash.Explicit.Prelude as CE
-import Clash.Prelude (Signal, type (*), type (+))
+import Clash.Prelude (type (*), type (+))
 import qualified Clash.Prelude as C
 
-import Protocols.Cpp (maxTupleSize)
+import Protocols.Circuit
 import Protocols.Internal.Classes
-import Protocols.Internal.TH (protocolTupleInstances)
 
 import Control.Arrow ((***))
 import Data.Coerce (coerce)
@@ -53,42 +52,6 @@ newtype Ack = Ack Bool
 instance Default Ack where
   def = Ack True
 
-{- | Circuit protocol with /Signal dom a/ in its forward direction, and
-/()/ in its backward direction. Convenient for exposing protocol
-internals, or simply for undirectional streams.
-
-Note: 'CSignal' exists to work around [issue 760](https://github.com/clash-lang/clash-compiler/issues/760)
-      in Clash, where type families with 'Signal' on the LHS are broken.
--}
-data CSignal (dom :: CE.Domain) (a :: Type)
-
-type role CSignal nominal representational
-
-instance Protocol () where
-  type Fwd () = ()
-  type Bwd () = ()
-
-{- | __NB__: The documentation only shows instances up to /3/-tuples. By
-default, instances up to and including /12/-tuples will exist. If the flag
-@large-tuples@ is set instances up to the GHC imposed limit will exist. The
-GHC imposed limit is either 62 or 64 depending on the GHC version.
--}
-instance Protocol (a, b) where
-  type Fwd (a, b) = (Fwd a, Fwd b)
-  type Bwd (a, b) = (Bwd a, Bwd b)
-
--- Generate n-tuple instances, where n > 2
-protocolTupleInstances 3 maxTupleSize
-
-instance (C.KnownNat n) => Protocol (C.Vec n a) where
-  type Fwd (C.Vec n a) = C.Vec n (Fwd a)
-  type Bwd (C.Vec n a) = C.Vec n (Bwd a)
-
--- XXX: Type families with Signals on LHS are currently broken on Clash:
-instance Protocol (CSignal dom a) where
-  type Fwd (CSignal dom a) = Signal dom a
-  type Bwd (CSignal dom a) = Signal dom ()
-
 {- | Left-to-right circuit composition.
 
 @