trace -package:matrix

The trace function outputs the trace message given as its first argument, before returning the second argument as its result. For example, this returns the value of f x and outputs the message to stderr. Depending on your terminal (settings), they may or may not be mixed.

>>> let x = 123; f = show

>>> trace ("calling f with x = " ++ show x) (f x)
calling f with x = 123
"123"

The trace function should only be used for debugging, or for monitoring execution. The function is not referentially transparent: its type indicates that it is a pure function but it has the side effect of outputting the trace message.

trace :: ToJExpr a => a -> JStat

ghc GHC.JS.Make

trace :: (Trace m, Num a) => m (m a) -> a

linear Linear.Matrix Linear.Trace

Compute the trace of a matrix

>>> trace (V2 (V2 a b) (V2 c d))
a + d

trace :: (Trace m, Foldable m, Num a) => m (m a) -> a

linear Linear.Matrix Linear.Trace

Compute the trace of a matrix

>>> trace (V2 (V2 a b) (V2 c d))
a + d

trace :: ComonadTraced m w => m -> w a -> a

comonad Control.Comonad.Traced Control.Comonad.Traced.Class

trace :: Comonad w => m -> TracedT m w a -> a

comonad Control.Comonad.Trans.Traced

trace :: PandocMonad m => Text -> m ()

pandoc Text.Pandoc.Class

Output a debug message to sterr, using trace, if tracing is enabled. Note: this writes to stderr even in pure instances.

trace :: Int -> IOStateArrow s b String -> IOStateArrow s b b

hxt Text.XML.HXT.Arrow.XmlState Text.XML.HXT.Arrow.XmlState.TraceHandling

apply a trace arrow and issue message to stderr

trace :: Print b => b -> a -> a

protolude Protolude.Debug

Warning: trace remains in code

trace :: forall (v :: Type -> Type) n m b . (Metric v, OrderedField n, Semigroup m) => Lens' (QDiagram b v n m) (Trace v n)

diagrams-lib Diagrams.Trace

Lens onto the Trace of a QDiagram.

trace :: forall r_aCco . Member Trace r_aCco => String -> Sem r_aCco ()

polysemy Polysemy.Trace

Log a message.

trace :: String -> a -> a

relude Relude.Debug

Warning: trace remains in code

trace :: Text -> a -> a

rio RIO

Warning: Trace statement left in code

trace :: String -> a -> a

base-prelude BasePrelude

The trace function outputs the trace message given as its first argument, before returning the second argument as its result. For example, this returns the value of f x but first outputs the message.

>>> let x = 123; f = show

>>> trace ("calling f with x = " ++ show x) (f x)
"calling f with x = 123
123"

trace :: Text -> Sh ()

shelly Shelly

Internally log what occurred. Log will be re-played on failure.

trace :: MonadSh m => Text -> m ()

shelly Shelly.Lifted

trace :: Text -> Sh ()

shelly Shelly.Pipe

see trace

trace :: String -> a -> a

classy-prelude ClassyPrelude

Warning: Leaving traces in the code

trace :: (Metric v, OrderedField n, Semigroup m) => Lens' (QDiagram b v n m) (Trace v n)

diagrams-core Diagrams.Core Diagrams.Core.Types

Lens onto the Trace of a QDiagram.

trace :: (IsStream t, MonadAsync m) => (a -> m b) -> t m a -> t m a

streamly Streamly.Internal.Data.Stream.IsStream.Transform Streamly.Prelude

Apply a monadic function to each element flowing through the stream and discard the results.

>>> Stream.drain $ Stream.trace print (Stream.enumerateFromTo 1 2)
1
2

Compare with tap.

trace :: HasTrace s a => Lens' s a

lsp-types Language.LSP.Protocol.Lens

trace :: Text -> a -> a

universum Universum.Debug

Warning: trace remains in code

trace :: Has Trace sig m => String -> m ()

fused-effects Control.Effect.Trace

Append a message to the trace log.

trace :: String -> a -> a

Cabal-syntax Distribution.Compat.Prelude

Deprecated: Don't leave me in the code

trace :: Member Trace r => String -> Eff r ()

extensible-effects Control.Eff.Trace

Print a string as a trace.