-- | functions that help you with debugging.
-- Most would make sense in the Debug.Trace module
module Debug.Util 
  (debug, debugM, debugMsg, ltrace, ltraceM, strace, traceId)
  where

import Debug.Trace (trace)

-- | A version of Debug.Trace.trace that just prints a value.
-- This should be included in Debug.Trace
debug :: Show a => a -> a
debug = ltrace "DEBUG"

-- | A version of Debug.Trace.trace that just prints a value and a message.
-- This should be included in Debug.Trace
debugMsg :: Show a => String -> a -> a
debugMsg msg = ltrace ("DEBUG: " ++ msg)


-- | monadic debug - like debug, but works as a standalone line in a monad
-- TODO: TH version with error loaction info
debugM :: (Monad m, Show a) => a -> m a
debugM a = debug a `seq` return a

-- | trace (print on stdout at runtime) a showable expression
-- like debug, but does not print "DEBUG: "
-- traceId is an alias for strace
-- strace stands for "show trace"
-- traceId means it returns itself after tracing like the id function
strace, traceId :: Show a => a -> a
strace a = trace (show a) a

traceId = strace

-- | labelled trace - like strace, with a label prepended
ltrace :: Show a => String -> a -> a
ltrace l a = trace (l ++ ": " ++ show a) a

-- | monadic debug - like debug, but works as a standalone line in a monad
-- TODO: TH version with error loaction info
ltraceM :: (Monad m, Show a) => String -> a -> m a
ltraceM str a = ltrace str a `seq` return a