vmcompiler: prefix labels with current function name

src/Nand2Tetris/VM.hs

@@ -22,6 +22,7 @@ module Nand2Tetris.VM
 import           Control.Monad.State.Strict (State, evalState, forM, gets,
                                              modify')
 import           Data.Functor               (($>))
+import           Data.Maybe                 (fromMaybe)
 import qualified Data.Text                  as T
 import           Nand2Tetris.Error          (Error)
 import           Nand2Tetris.Hack           (HackInstruction (A, C),
@@ -290,16 +291,20 @@ compileInstruction instr = do
     compileInstruction' (VMArithmetic ACAnd) = return $ binopSequence SDAndM
     compileInstruction' (VMArithmetic ACOr) = return $ binopSequence SDOrM
     compileInstruction' (VMArithmetic ACNot) = return $ unopSequence (SNot RegM)
-    compileInstruction' (VMBranching (BLabel label)) = return [ALabel label]
-    compileInstruction' (VMBranching (BGoto label)) =
-      return [ Code (A (Label label)),
+    compileInstruction' (VMBranching (BLabel label)) = do
+      fname <- fromMaybe "_Global" <$> gets ceCurrentFunction
+      return [ALabel $ fname <> "$" <> label]
+    compileInstruction' (VMBranching (BGoto label)) = do
+      fname <- fromMaybe "_Global" <$> gets ceCurrentFunction
+      return [ Code (A (Label $ fname <> "$" <> label)),
                Code (C [] S0 Jmp)
              ]
-    compileInstruction' (VMBranching (BIfGoto label)) =
+    compileInstruction' (VMBranching (BIfGoto label)) = do
+      fname <- fromMaybe "_Global" <$> gets ceCurrentFunction
       return [ Code (A (Label "SP")),
                Code (C [RegA, RegM] (SRegMinus1 RegM) JNone),
                Code (C [RegD] (SReg RegM) JNone),
-               Code (A (Label label)),
+               Code (A (Label $ fname <> "$" <> label)),
                Code (C [] (SReg RegD) JNe)
              ]
     compileInstruction' (VMFunction (FFunction name nvars)) = do