+
+type FlattenState = State.State ([App], [CondDef], SignalId)
+
+-- | Add an application to the current FlattenState
+addApp :: App -> FlattenState ()
+addApp a = do
+ (apps, conds, n) <- State.get
+ State.put (a:apps, conds, n)
+
+-- | Add a conditional definition to the current FlattenState
+addCondDef :: CondDef -> FlattenState ()
+addCondDef c = do
+ (apps, conds, n) <- State.get
+ State.put (apps, c:conds, n)
+
+-- | Generates a new signal id, which is unique within the current flattening.
+genSignalId :: FlattenState SignalId
+genSignalId = do
+ (apps, conds, n) <- State.get
+ State.put (apps, conds, n+1)
+ return n
+
+genSignalUses ::
+ Type.Type
+ -> FlattenState SignalUseMap
+
+genSignalUses ty = do
+ typeMapToUseMap tymap
+ where
+ -- First generate a map with the right structure containing the types
+ tymap = mkHsValueMap ty
+
+typeMapToUseMap ::
+ HsValueMap Type.Type
+ -> FlattenState SignalUseMap
+
+typeMapToUseMap (Single ty) = do
+ id <- genSignalId
+ return $ Single (SignalUse id)
+
+typeMapToUseMap (Tuple tymaps) = do
+ usemaps <- mapM typeMapToUseMap tymaps
+ return $ Tuple usemaps
+
+-- | Flatten a haskell function
+flattenFunction ::
+ HsFunction -- ^ The function to flatten
+ -> CoreBind -- ^ The function value
+ -> FlatFunction -- ^ The resulting flat function
+
+flattenFunction _ (Rec _) = error "Recursive binders not supported"
+flattenFunction hsfunc bind@(NonRec var expr) =
+ FlatFunction args res apps conds
+ where
+ init_state = ([], [], 0)
+ (fres, end_state) = State.runState (flattenExpr [] expr) init_state
+ (args, res) = fres
+ (apps, conds, _) = end_state
+
+flattenExpr ::
+ BindMap
+ -> CoreExpr
+ -> FlattenState ([SignalDefMap], SignalUseMap)
+
+flattenExpr binds lam@(Lam b expr) = do
+ -- Find the type of the binder
+ let (arg_ty, _) = Type.splitFunTy (CoreUtils.exprType lam)
+ -- Create signal names for the binder
+ defs <- genSignalUses arg_ty
+ let binds' = (b, Left defs):binds
+ (args, res) <- flattenExpr binds' expr
+ return ((useMapToDefMap defs) : args, res)
+
+flattenExpr binds (Var id) =
+ case bind of
+ Left sig_use -> return ([], sig_use)
+ Right _ -> error "Higher order functions not supported."
+ where
+ bind = Maybe.fromMaybe
+ (error $ "Argument " ++ Name.getOccString id ++ "is unknown")
+ (lookup id binds)
+
+flattenExpr _ _ = do
+ return ([], Tuple [])
+
+