Implement Debug.Trace.Linear (#174)

linear-base.cabal

@@ -40,6 +40,7 @@ library
     Data.Profunctor.Linear
     Data.Profunctor.Kleisli.Linear
     Data.Unrestricted.Linear
+    Debug.Trace.Linear
     Foreign.Marshal.Pure
     Prelude.Linear
     System.IO.Linear

src/Debug/Trace/Linear.hs

@@ -0,0 +1,92 @@
+{-# LANGUAGE LinearTypes #-}
+{-# LANGUAGE NoImplicitPrelude #-}
+
+{-|
+A thin wrapper on top of "Debug.Trace", providing linear versions of
+tracing functions.
+
+It only contains minimal amount of documentation; you should consult
+the original "Debug.Trace" module for more detailed information.
+-}
+module Debug.Trace.Linear
+  ( -- * Tracing
+    trace
+  , traceShow
+  , traceId
+  , traceStack
+  , traceIO
+  , traceM
+  , traceShowM
+    -- * Eventlog tracing
+  , traceEvent
+  , traceEventIO
+    -- * Execution phase markers
+  , traceMarker
+  , traceMarkerIO
+  ) where
+
+import qualified Debug.Trace as NonLinear
+import qualified Unsafe.Linear as Unsafe
+import System.IO.Linear
+import Data.Functor.Linear
+import Data.Unrestricted.Linear
+import Prelude (String, Show(..))
+import Prelude.Linear.Internal
+
+-- | The 'trace' function outputs the trace message given as its first
+-- argument, before returning the second argument as its result.
+trace :: String #-> a #-> a
+trace = Unsafe.toLinear2 NonLinear.trace
+
+-- | Like 'trace', but uses 'show' on the argument to convert it to
+-- a 'String'.
+traceShow :: Show a => a -> b #-> b
+traceShow a = Unsafe.toLinear (NonLinear.traceShow a)
+
+-- | Like 'trace' but returns the message instead of a third value.
+traceId :: String #-> String
+traceId s = dup s & \(s', s'') -> trace s' s''
+
+-- | Like 'trace', but additionally prints a call stack if one is
+-- available.
+traceStack :: String #-> a #-> a
+traceStack = Unsafe.toLinear2 NonLinear.traceStack
+
+-- | The 'traceIO' function outputs the trace message from the IO monad.
+-- This sequences the output with respect to other IO actions.
+traceIO :: String #-> IO ()
+traceIO s = fromSystemIO (Unsafe.toLinear NonLinear.traceIO s)
+
+-- | Like 'trace' but returning unit in an arbitrary 'Applicative'
+-- context. Allows for convenient use in do-notation.
+traceM :: Applicative f => String #-> f ()
+traceM s = trace s $ pure ()
+
+-- | Like 'traceM', but uses 'show' on the argument to convert it to a
+-- 'String'.
+traceShowM :: (Show a, Applicative f) => a -> f ()
+traceShowM a = traceM (show a)
+
+-- | The 'traceEvent' function behaves like 'trace' with the difference
+-- that the message is emitted to the eventlog, if eventlog profiling is
+-- available and enabled at runtime.
+traceEvent :: String #-> a #-> a
+traceEvent = Unsafe.toLinear2 NonLinear.traceEvent
+
+-- | The 'traceEventIO' function emits a message to the eventlog, if
+-- eventlog profiling is available and enabled at runtime.
+traceEventIO :: String #-> IO ()
+traceEventIO s = fromSystemIO (Unsafe.toLinear NonLinear.traceEventIO s)
+
+-- | The 'traceMarker' function emits a marker to the eventlog, if eventlog
+-- profiling is available and enabled at runtime. The @String@ is the name
+-- of the marker. The name is just used in the profiling tools to help you
+-- keep clear which marker is which.
+traceMarker :: String #-> a #-> a
+traceMarker = Unsafe.toLinear2 NonLinear.traceMarker
+
+-- | The 'traceMarkerIO' function emits a marker to the eventlog, if
+-- eventlog profiling is available and enabled at runtime.
+traceMarkerIO :: String #-> IO ()
+traceMarkerIO s = fromSystemIO (Unsafe.toLinear NonLinear.traceMarkerIO s)
+