diff --git a/changelog.md b/changelog.md
--- a/changelog.md
+++ b/changelog.md
@@ -1,5 +1,8 @@
 # trace-embrace changelog
 
+## Version 1.1.0 2025-06-04
+  * add `a`, `u` and `tg` for tracing guarded functions
+
 ## Version 1.0.8 2025-03-14
   * bugfix: serialize test compilation with [th-lock](https://hackage.haskell.org/package/th-lock)
   * bugfix: serialize yaml config loading and on demand initialization
diff --git a/src/Debug/TraceEmbrace/FileIndex.hs b/src/Debug/TraceEmbrace/FileIndex.hs
--- a/src/Debug/TraceEmbrace/FileIndex.hs
+++ b/src/Debug/TraceEmbrace/FileIndex.hs
@@ -28,7 +28,7 @@
 import Unsafe.Coerce
 
 
-newtype FunName = FunName String deriving (Show, Eq, Ord, IsString, Lift)
+newtype FunName = FunName { unFunName :: String } deriving (Show, Eq, Ord, IsString, Lift)
 type LineFileIndex = IM.IntMap FunName
 
 unsafeRunTcM :: TcM a -> Q a
diff --git a/src/Debug/TraceEmbrace/Internal/TH.hs b/src/Debug/TraceEmbrace/Internal/TH.hs
--- a/src/Debug/TraceEmbrace/Internal/TH.hs
+++ b/src/Debug/TraceEmbrace/Internal/TH.hs
@@ -25,8 +25,8 @@
 import System.IO.Unsafe (unsafePerformIO)
 import Text.Printf
 
-newtype TrMsgAndVars = TrMsgAndVars String deriving (Eq, P.Show)
-newtype VarsPart = VarsPart String deriving (Eq, P.Show)
+data TrMsgAndVars = TrMsgAndVars [Name] String  deriving (Eq, P.Show)
+data VarsPart = VarsPart [Name] String deriving (Eq, P.Show)
 newtype ModTraceFlagVarName = ModTraceFlagVarName Name deriving (Eq, P.Show)
 
 type SVarsFunM a = StateT (Maybe Name) Q a
@@ -110,17 +110,22 @@
 
 -}
 svars :: SVarsFun
-svars tmf (VarsPart vars) = MT.lift $
+svars tmf (VarsPart patVars vars) = MT.lift $
   case span (';' /=) vars of
     (showVars, ';' : traceVars) ->
-      [| $(listE (wordsToVars 'show showVars
-                   <> wordsToVars 'showTrace traceVars)) :: [String] |]
+      [| $(listE (noTraceVars showVars <> wordsToVars 'showTrace traceVars)) :: [String] |]
     (showVars, "") ->
-      [| $(listE (wordsToVars 'show showVars)) :: [String] |]
+      [| $(listE (noTraceVars showVars)) :: [String] |]
     (sv, st) -> do
       reportError $ printf "No case for %s %s" sv st
       [| [] |]
   where
+    noTraceVars showVars =
+      wordsToVars 'show showVars <> zipWith (name2Var 'show) [0 :: Int ..] patVars
+
+    name2Var f 0 vn = [| $(lift . unrefine $ tmf ^. #entrySeparator) <> $(varE f) $(varE vn) |]
+    name2Var f _ vn = [| " " <> $(varE f) $(varE vn) |]
+
     wordsToVars f vss = fmap go (varNamesFromPat vss)
       where
         go vs =
@@ -136,14 +141,14 @@
                |]
 
 splitMessageFromVars :: TrMsgAndVars -> (String, VarsPart)
-splitMessageFromVars (TrMsgAndVars trMsg) =
+splitMessageFromVars (TrMsgAndVars patVars trMsg) =
   case span ('/' /=) trMsg of
-    (msgPart, '/':varPart) -> (msgPart, VarsPart varPart)
-    (msgPart, []) -> (msgPart, VarsPart [])
+    (msgPart, '/':varPart) -> (msgPart, VarsPart patVars varPart)
+    (msgPart, []) -> (msgPart, VarsPart patVars [])
     e ->  error $ "No case for:" <> show e
 
-traceMessageLevel :: String -> (TraceLevel, TrMsgAndVars)
-traceMessageLevel = fmap TrMsgAndVars . charToLevel
+traceMessageLevel :: [Name] -> String -> (TraceLevel, TrMsgAndVars)
+traceMessageLevel patVars = fmap (TrMsgAndVars patVars) . charToLevel
 
 -- | Suffix 'svars' with return value.
 svarsWith :: SVarsFun
@@ -160,6 +165,19 @@
 concat2 = mconcat . mconcat
 {-# INLINE concat2 #-}
 
+currentFunName :: Q FunName
+currentFunName = do
+  lc <- location
+  let
+    m = loc_module lc
+    line = fst $ loc_start lc
+  fmap snd . IM.lookupLE line <$> getLineFileIndex lc >>= \case
+    Nothing -> do
+      reportWarning (printf "No function name for line [%d] in module [%s]" line m)
+      pure $ FunName "N/A"
+    Just fn -> pure fn
+  where
+
 -- | Format whole trace message
 traceMessage :: TrMsgAndVars -> TraceMessageFormat -> SVarsFun -> Q Exp
 traceMessage mavs tmf svarsFun =
@@ -185,16 +203,7 @@
         (eludom, htap) <- span (/= '.') . reverse . loc_module <$> loc
         pStrL $ shortenModPath True (reverse htap) <> (reverse eludom)
       PackageName -> strL . loc_package <$> loc
-      FunctionName -> do
-        lc <- loc
-        let
-          m = loc_module lc
-          line = fst $ loc_start lc
-        strL <$> MT.lift (fmap snd . IM.lookupLE line <$> getLineFileIndex lc >>= \case
-          Nothing -> do
-            reportWarning (printf "No function name for line [%d] in module [%s]" line m)
-            pure "N/A"
-          Just (FunName fn) -> pure fn)
+      FunctionName -> strL <$> MT.lift (unFunName <$> currentFunName)
       LineNumber -> strL . P.show . fst . loc_start <$> loc
       Delimiter del -> pStrL del
 
@@ -245,8 +254,13 @@
           atomicWriteIORef fv (Just False) >> pure False
 {-# INLINE readTraceFlag #-}
 
-traceG :: TraceEmbraceConfig -> Q Exp -> (TrMsgAndVars -> TraceMessageFormat -> Q Exp) -> String -> Q Exp
-traceG c idF genTraceLine s =
+traceG :: TraceEmbraceConfig ->
+  Q Exp ->
+  (TrMsgAndVars -> TraceMessageFormat -> Q Exp) ->
+  String ->
+  [Name] ->
+  Q Exp
+traceG c idF genTraceLine s patVars =
   case c ^. #mode of
     TraceDisabled -> idF
     TraceStd -> go
@@ -254,7 +268,7 @@
     TraceEvent -> go
   where
     go =
-      case traceMessageLevel s of
+      case traceMessageLevel patVars s of
         (TracingDisabled, _) -> idF
         (tl, s') -> do
           loc <- location
@@ -308,9 +322,12 @@
     TraceEvent -> pure $ VarE 'T.traceEvent
 
 tr :: Q Exp -> String -> Q Exp
-tr idF rawMsg = do
+tr idF rawMsg = tr' idF rawMsg []
+
+tr' :: Q Exp -> String -> [Name]-> Q Exp
+tr' idF rawMsg patVars = do
   c <- getConfig
-  traceG c idF (go c) rawMsg
+  traceG c idF (go c) rawMsg patVars
   where
     go c s fmt =
       [| \x -> unwrap ($(chooseTraceFunOnTh c s) $(traceMessage s fmt svars) (wrap x)) |]
@@ -318,7 +335,7 @@
 tw :: Q Exp -> String -> Q Exp
 tw idF rawMsg = do
   c <- getConfig
-  traceG c idF (go c) rawMsg
+  traceG c idF (go c) rawMsg []
   where
     go c s fmt =
       [| \x -> unwrap ($(chooseTraceFunOnTh c s)
@@ -329,7 +346,7 @@
 tw' :: Q Exp -> String -> Q Exp
 tw' idF rawMsg = do
   c <- getConfig
-  traceG c idF (go c) rawMsg
+  traceG c idF (go c) rawMsg []
   where
     go c s fmt =
       [| \x -> unwrap ($(chooseTraceFunOnTh c s)
@@ -348,7 +365,7 @@
 trIo :: Q Exp -> String -> Q Exp
 trIo idF rawMsg = do
   c <- getConfig
-  traceG c idF (go c) rawMsg
+  traceG c idF (go c) rawMsg []
   where
     go c s fmt =
       [| $(chooseTraceIoFunOnTh c s) $(traceMessage s fmt svars) |]
@@ -357,7 +374,7 @@
 trFunMarker idF = do
   c <- getConfig
   let finalC = if c ^. #mode == TraceDisabled then c else markerConfig
-  traceG finalC idF go "/"
+  traceG finalC idF go "/" []
   where
     go s fmt =
       [| \x -> unwrap (T.traceMarker $(traceMessage s fmt svars) (wrap x)) |]
@@ -366,7 +383,7 @@
 trIoFunMarker idF = do
   c <- getConfig
   let finalC = if c ^. #mode == TraceDisabled then c else markerConfig
-  traceG finalC idF go "/"
+  traceG finalC idF go "/" []
   where
     go s fmt =
       [| T.traceMarkerIO $(traceMessage s fmt svars) |]
diff --git a/src/Debug/TraceEmbrace/TH.hs b/src/Debug/TraceEmbrace/TH.hs
--- a/src/Debug/TraceEmbrace/TH.hs
+++ b/src/Debug/TraceEmbrace/TH.hs
@@ -1,14 +1,16 @@
 {-# OPTIONS_HADDOCK hide, prune #-}
 
 -- | Tracing with TH
-module Debug.TraceEmbrace.TH (tr, tw, tw', trIo, trFunMarker, trIoFunMarker) where
+module Debug.TraceEmbrace.TH (tr, tw, tw', trIo, u, a, s_, tg, tg', underbar, trFunMarker, trIoFunMarker) where
 
 import Debug.Trace
 import Debug.TraceEmbrace.Config
+import Debug.TraceEmbrace.FileIndex (FunName (..))
 import Debug.TraceEmbrace.Internal.Rewrap
 import Debug.TraceEmbrace.Internal.TH qualified as I
 import Haddock.UseRefs
 import Language.Haskell.TH
+import Language.Haskell.TH.Syntax
 
 countDocRefs
 
@@ -24,8 +26,7 @@
 --
 -- > Module::foo get; x : 132
 tr :: String -> Q Exp
-tr = I.tr [| \x -> x |]
-
+tr tm = I.tr [| \x -> x |] tm
 
 -- | TH version of 'traceWith' and 'traceEventWith'
 -- The message is formatted according to 'TraceMessageFormat'.
@@ -66,3 +67,71 @@
 -- are used as a marker. Trace level is not used.
 trIoFunMarker :: Q Exp
 trIoFunMarker = I.trIoFunMarker [| pure () |]
+
+data ArgPatCounter
+  = ArgPatCounter
+    { funName :: FunName
+    , argNames :: [Name]
+    } deriving (Show)
+
+data Undebar = Undebar
+
+instance Show Undebar where
+  show _ = "_"
+
+underbar :: Undebar
+underbar = Undebar
+-- | Generates consequent pattern variable for tracing arguments of a guarded function.
+-- It is assumed that 'a' is used together with 'tg' and 'u'.
+--
+-- > foo $a $a $a | $tg = $u
+-- > foo 0  _  _ = 0
+-- > foo x y z = x + y + z
+--
+a :: Q Pat
+a = do
+  cfn <- I.currentFunName
+  getQ >>= \case
+    Nothing -> reset cfn
+    Just (ArgPatCounter fn aNames)
+      | fn == cfn -> go aNames cfn
+      | otherwise -> reset cfn
+  where
+    reset cfn = go [] cfn
+    go ans cfn = do
+      nn <- newName $ "traceEmbracePatArg" <> (show $ length ans)
+      putQ (ArgPatCounter cfn $ nn : ans)
+      varP nn
+
+-- | Similar to 'a', but argument is not included in trace message.
+s_ :: Q Pat
+s_ = do
+  cfn <- I.currentFunName
+  getQ >>= \case
+    Nothing -> reset cfn
+    Just (ArgPatCounter fn aNames)
+      | fn == cfn -> go aNames cfn
+      | otherwise -> reset cfn
+  where
+    reset cfn = go [] cfn
+    go ans cfn = putQ (ArgPatCounter cfn $ 'underbar : ans) >> [p|_|]
+
+-- | Expands to @$(tr "/a b c d...") False@
+tg :: Q Exp
+tg = tg' ""
+
+-- | Similar to 'tg' with message prefix with the argument.
+tg' :: String -> Q Exp
+tg' msgPrefix = do
+  cfn <- I.currentFunName
+  getQ >>= \case
+    Nothing -> er
+    Just (ArgPatCounter fn aNames)
+      | fn == cfn -> [|$(I.tr' [| \x -> x |] msgPrefix $ reverse aNames) False|]
+      | otherwise -> er
+  where
+    er = fail "Use 'Debug.TraceEmbrace.TH.a' macro to capture function arguments before calling 'tg'"
+
+-- | Shortcut for 'undefined'
+u :: Q Exp
+u = [| undefined |]
diff --git a/test/Debug/TraceEmbrace/Test/TraceEmbrace/Config.hs b/test/Debug/TraceEmbrace/Test/TraceEmbrace/Config.hs
--- a/test/Debug/TraceEmbrace/Test/TraceEmbrace/Config.hs
+++ b/test/Debug/TraceEmbrace/Test/TraceEmbrace/Config.hs
@@ -47,10 +47,10 @@
   }
 
 trConstMsg :: String -> Q Exp
-trConstMsg msgAndVars = traceMessage (TrMsgAndVars msgAndVars) msgAndVarsOnly svars
+trConstMsg msgAndVars = traceMessage (TrMsgAndVars [] msgAndVars) msgAndVarsOnly svars
 
 trFunMsg :: String -> Q Exp
-trFunMsg msgAndVars = traceMessage (TrMsgAndVars msgAndVars) msgAndVarsOnly svarsWith
+trFunMsg msgAndVars = traceMessage (TrMsgAndVars [] msgAndVars) msgAndVarsOnly svarsWith
 
 one :: Int
 one = 1
diff --git a/test/Debug/TraceEmbrace/Test/TraceEmbrace/GuardedFunction.hs b/test/Debug/TraceEmbrace/Test/TraceEmbrace/GuardedFunction.hs
new file mode 100644
--- /dev/null
+++ b/test/Debug/TraceEmbrace/Test/TraceEmbrace/GuardedFunction.hs
@@ -0,0 +1,30 @@
+-- {-# OPTIONS_GHC -ddump-splices #-}
+module Debug.TraceEmbrace.Test.TraceEmbrace.GuardedFunction where
+
+import Debug.TraceEmbrace
+import Debug.TraceEmbrace.Test.TraceEmbrace.Config
+import Language.Haskell.TH.Lock
+import Test.Tasty.HUnit ((@=?))
+
+ensureSerialCompilationVerbose
+
+sum4 :: (Show a, Num a) => a -> a -> a -> a -> a
+sum4 $a $a $s_ $a | $tg = $u
+sum4 a1 a2 a3 a4 = a1 + a2 + a3 + a4
+
+unit_sum4_a_tg_u :: IO ()
+unit_sum4_a_tg_u = withPrefixEnvVar thresholdConfig "" $ sum4 one one one one @=? 4
+
+sum1 :: Show a => a -> a
+sum1 $a | $tg = $u
+sum1 a1 = a1
+
+unit_sum1_a_tg_u :: IO ()
+unit_sum1_a_tg_u = withPrefixEnvVar thresholdConfig "" $ sum1 one @=? 1
+
+sum2 :: (Show a, Num a) => a -> a -> a
+sum2 $a $a | $(tg' "sum2/") = $u
+sum2 a1 a2 = a1 + a2
+
+unit_sum2_a_tg_u :: IO ()
+unit_sum2_a_tg_u = withPrefixEnvVar thresholdConfig "" $ sum2 one one @=? 2
diff --git a/test/Debug/TraceEmbrace/Test/TraceEmbrace/TH/Format/Lifted.hs b/test/Debug/TraceEmbrace/Test/TraceEmbrace/TH/Format/Lifted.hs
--- a/test/Debug/TraceEmbrace/Test/TraceEmbrace/TH/Format/Lifted.hs
+++ b/test/Debug/TraceEmbrace/Test/TraceEmbrace/TH/Format/Lifted.hs
@@ -13,7 +13,7 @@
 unit_traceMessage_const :: IO ()
 unit_traceMessage_const =
   ("Debug.TraceEmbrace.Test.TraceEmbrace.TH.Format.Lifted::unit_traceMessage_const" :: String) @=?
-     $(traceMessage (TrMsgAndVars "skipped") positionOnly svars)
+     $(traceMessage (TrMsgAndVars [] "skipped") positionOnly svars)
 
 unit_traceMessage_fun :: IO ()
 unit_traceMessage_fun = ("foo => True" :: String) @=?  $(trFunMsg "foo") True
diff --git a/test/Debug/TraceEmbrace/Test/TraceEmbrace/TH/Line.hs b/test/Debug/TraceEmbrace/Test/TraceEmbrace/TH/Line.hs
--- a/test/Debug/TraceEmbrace/Test/TraceEmbrace/TH/Line.hs
+++ b/test/Debug/TraceEmbrace/Test/TraceEmbrace/TH/Line.hs
@@ -8,4 +8,4 @@
 
 unit_traceMessage_line :: IO ()
 unit_traceMessage_line =
-  ("11:" :: String) @=? $(traceMessage (TrMsgAndVars "skipped") lineOnly svars)
+  ("11:" :: String) @=? $(traceMessage (TrMsgAndVars [] "skipped") lineOnly svars)
diff --git a/trace-embrace.cabal b/trace-embrace.cabal
--- a/trace-embrace.cabal
+++ b/trace-embrace.cabal
@@ -1,6 +1,6 @@
 cabal-version:   3.0
 name:            trace-embrace
-version:         1.0.11
+version:         1.1.0
 license:         BSD-3-Clause
 license-file:    LICENSE
 category:        Development
@@ -258,6 +258,22 @@
     
     Module:fun: 7 get; x: 1; y: 2; z: 3 => 6
     
+    === Guarded function
+    #guarded-function#
+    
+    > {-# LANGUAGE TemplateHaskell #-}
+    > module Module where
+    >
+    > import Debug.TraceEmbrace
+    >
+    > fun :: Int -> Int -> Int -> Int
+    > fun $a $a_ $a | $tg = $u
+    > fun a b c = a + b + c
+    
+    A trace line for the snippet above would be:
+    
+    Module:fun: 7; 1 _ 3
+    
     === Trace lazy ByteString structure
     #trace-lazy-bytestring-structure#
     
@@ -398,6 +414,7 @@
     Debug.TraceEmbrace.Test.TraceEmbrace.Config
     Debug.TraceEmbrace.Test.TraceEmbrace.DemoIndex
     Debug.TraceEmbrace.Test.TraceEmbrace.FileIndex
+    Debug.TraceEmbrace.Test.TraceEmbrace.GuardedFunction
     Debug.TraceEmbrace.Test.TraceEmbrace.TH
     Debug.TraceEmbrace.Test.TraceEmbrace.TH.Event
     Debug.TraceEmbrace.Test.TraceEmbrace.TH.Format.Lifted