[commit: ghc] master: Add pprTraceM to Outputable as analog to traceM. (126b412)

[git at git.haskell.org]

Repository : ssh://git@git.haskell.org/ghc

On branch  : master
Link       : http://ghc.haskell.org/trac/ghc/changeset/126b4125d95f7e4d272a9307cb8b634b11bd337f/ghc

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commit 126b4125d95f7e4d272a9307cb8b634b11bd337f
Author: klebinger.andreas at gmx.at <klebinger.andreas at gmx.at>
Date:   Wed May 16 12:11:27 2018 -0400

    Add pprTraceM to Outputable as analog to traceM.
    
    Test Plan: ci, using it in monadic code.
    
    Reviewers: bgamari, mpickering
    
    Reviewed By: mpickering
    
    Subscribers: rwbarton, thomie, carter
    
    Differential Revision: https://phabricator.haskell.org/D4697


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126b4125d95f7e4d272a9307cb8b634b11bd337f
 compiler/utils/Outputable.hs | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/compiler/utils/Outputable.hs b/compiler/utils/Outputable.hs
index e435734..2b89162 100644
--- a/compiler/utils/Outputable.hs
+++ b/compiler/utils/Outputable.hs
@@ -82,7 +82,7 @@ module Outputable (
         -- * Error handling and debugging utilities
         pprPanic, pprSorry, assertPprPanic, pprPgmError,
         pprTrace, pprTraceDebug, pprTraceIt, warnPprTrace, pprSTrace,
-        pprTraceException,
+        pprTraceException, pprTraceM,
         trace, pgmError, panic, sorry, assertPanic,
         pprDebugAndThen, callStackDoc,
     ) where
@@ -1182,6 +1182,9 @@ pprTrace str doc x
    | otherwise                             =
       pprDebugAndThen unsafeGlobalDynFlags trace (text str) doc x
 
+pprTraceM :: Applicative f => String -> SDoc -> f ()
+pprTraceM str doc = pprTrace str doc (pure ())
+
 -- | @pprTraceIt desc x@ is equivalent to @pprTrace desc (ppr x) x@
 pprTraceIt :: Outputable a => String -> a -> a
 pprTraceIt desc x = pprTrace desc (ppr x) x