diff options
Diffstat (limited to 'libraries/base/Debug/Trace.hs')
| -rw-r--r-- | libraries/base/Debug/Trace.hs | 35 |
1 files changed, 35 insertions, 0 deletions
diff --git a/libraries/base/Debug/Trace.hs b/libraries/base/Debug/Trace.hs index e85fb7590a..90aed3acb9 100644 --- a/libraries/base/Debug/Trace.hs +++ b/libraries/base/Debug/Trace.hs @@ -27,6 +27,8 @@ module Debug.Trace ( traceId, traceShow, traceShowId, + traceWith, + traceShowWith, traceStack, traceIO, traceM, @@ -36,6 +38,7 @@ module Debug.Trace ( -- * Eventlog tracing -- $eventlog_tracing traceEvent, + traceEventWith, traceEventIO, flushEventLog, @@ -164,6 +167,31 @@ traceShowId :: Show a => a -> a traceShowId a = trace (show a) a {-| +Like 'trace', but outputs the result of calling a function on the argument. + +>>> traceWith fst ("hello","world") +hello +("hello","world") + +@since 4.17.0.0 +-} +traceWith :: (a -> String) -> a -> a +traceWith f a = trace (f a) a + +{-| +Like 'traceWith', but uses 'show' on the result of the function to convert it to +a 'String'. + +>>> traceShowWith length [1,2,3] +3 +[1,2,3] + +@since 4.17.0.0 +-} +traceShowWith :: Show b => (a -> b) -> a -> a +traceShowWith f = traceWith (show . f) + +{-| Like 'trace' but returning unit in an arbitrary 'Applicative' context. Allows for convenient use in do-notation. @@ -272,6 +300,13 @@ traceEventIO msg = GHC.Foreign.withCString utf8 msg $ \(Ptr p) -> IO $ \s -> case traceEvent# p s of s' -> (# s', () #) +-- | Like 'traceEvent', but emits the result of calling a function on its +-- argument. +-- +-- @since 4.17.0.0 +traceEventWith :: (a -> String) -> a -> a +traceEventWith f a = traceEvent (f a) a + -- $markers -- -- When looking at a profile for the execution of a program we often want to |