-- Trying to see if a function type is synthesizable
-- Verdict: No, it isn't (compiles though).

import Clash.Prelude

tf :: (Int -> Bool) -> Int -> ((Int -> Bool), Bool)
tf s inp = (s', out)
  where
    out = s inp
    s' = \x -> not $ s x

mon
  :: SystemClockResetEnable
  => Signal System Int
  -> Signal System Bool
mon = mealy tf (\x -> True)

topEntity
  :: Clock System
  -> Reset System
  -> Enable System
  -> Signal System Int
  -> Signal System Bool
topEntity = exposeClockResetEnable mon


{-
GHC: Setting up GHC took: 0.673s
GHC: Compiling and loading modules took: 0.360s
Clash: Parsing and compiling primitives took 0.318s
GHC+Clash: Loading modules cumulatively took 1.459s
Clash: Compiling Main.topEntity
Clash: Normalization took 0.028s

/home/username/gits/playground/clash/FuncSyth.hs:26:1: error:
    
    Clash.Netlist(296): Clash.Netlist.Util(184): Not in normal form: no Letrec:
    
    λ(clk[6989586621679047087] :: Clash.Signal.Internal.Clock[8214565720323787981]
                                    "System") ->
    λ(rst[6989586621679047088] :: Clash.Signal.Internal.Reset[8214565720323788005]
                                    "System") ->
    λ(en[6989586621679047089] :: Clash.Signal.Internal.Enable[8214565720323787996]
                                   "System") ->
    λ(eta[4755801206503243777] :: Clash.Signal.Internal.Signal[8214565720323788026]
                                    "System"
                                    GHC.Types.Int[3674937295934324766]) ->
    <prefixName>"mon_ds"
    <prefixName>"tf"
    λ(c$arg[37] :: GHC.Types.Int[3674937295934324766]) ->
    let
      result[14304] :: GHC.Types.Bool[3674937295934324744]
      = Clash.Signal.Internal.register# @"System"
          @(GHC.Types.Int[3674937295934324766]
          -> GHC.Types.Bool[3674937295934324744])
          (Clash.Normalize.Primitives.removedArg
             @(Clash.Signal.Internal.KnownDomain[8214565720323788003]
                 "System"))
          (Clash.Normalize.Primitives.removedArg
             @(Clash.XException.NFDataX[8214565720323788071]
                 (GHC.Types.Int[3674937295934324766]
                 -> GHC.Types.Bool[3674937295934324744])))
          <prefixName>"$p1(%,,%)"
          clk[6989586621679047087][LocalId]
          <prefixName>"$p2(%,,%)"
          rst[6989586621679047088][LocalId]
          <prefixName>"$p3(%,,%)"
          en[6989586621679047089][LocalId]
          (λ(x[6989586621679042492] :: GHC.Types.Int[3674937295934324766]) ->
          GHC.Types.True[3891110078048108589])
          (λ(x[6989586621679042492] :: GHC.Types.Int[3674937295934324766]) ->
          GHC.Types.True[3891110078048108589])
          (λ(c$arg[1998] :: GHC.Types.Int[3674937295934324766]) ->
          <prefixName>"mon_ds"
          <prefixName>"tf"
          letrec
            c$app_arg[2002] :: GHC.Types.Bool[3674937295934324744]
            = c$Main.mon_s[20][GlobalId]
                eta[4755801206503243777][LocalId]
                clk[6989586621679047087][LocalId]
                rst[6989586621679047088][LocalId]
                en[6989586621679047089][LocalId]
            result[2003] :: GHC.Types.Bool[3674937295934324744]
            = <prefixName>"not"
                GHC.Classes.not
                c$app_arg[2002][LocalId]
          in result[2003][LocalId])
          c$arg[37][LocalId]
    in result[14304][LocalId]
    
    Which has type:
    
    Clash.Signal.Internal.Clock[8214565720323787981]
      "System"
    -> Clash.Signal.Internal.Reset[8214565720323788005]
         "System"
    -> Clash.Signal.Internal.Enable[8214565720323787996]
         "System"
    -> Clash.Signal.Internal.Signal[8214565720323788026]
         "System"
         GHC.Types.Int[3674937295934324766]
    -> GHC.Types.Int[3674937295934324766]
    -> GHC.Types.Bool[3674937295934324744]
    
    The source location of the error is not exact, only indicative, as it is acquired 
    after optimizations. The actual location of the error can be in a function that is 
    inlined. To prevent inlining of those functions, annotate them with a NOINLINE pragma.
   |
26 | topEntity = exposeClockResetEnable mon
   | ^^^^^^^^^
-}