[GHC] #11686: implicit call stacks should provide a way to get the calling function's name

7 Mar 2016

      #11686: implicit call stacks should provide a way to get the calling function's
name
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           Reporter:  elaforge       |             Owner:
               Type:  feature        |            Status:  new
  request                            |
           Priority:  normal         |         Milestone:
          Component:  Compiler       |           Version:  7.10.3
           Keywords:                 |  Operating System:  Unknown/Multiple
       Architecture:                 |   Type of failure:  None/Unknown
  Unknown/Multiple                   |
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):                 |         Wiki Page:
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 With implicit call stacks we can get the calling SrcPos and the called
 function's name, but not the caller function's name.  E.g.:

 {{{#!hs
 {-# LANGUAGE ImplicitParams, ConstraintKinds #-}
 import qualified GHC.Stack as Stack

 caller :: IO ()
 caller = callee 10
     where
     callee :: (?stack :: Stack.CallStack) => Int -> IO ()
     callee _n = mapM_ print (Stack.getCallStack ?stack)
 }}}

 Gives

 {{{
 ("?stack",SrcLoc {srcLocPackage = "main", srcLocModule = "Main",
 srcLocFile = "T.hs", srcLocStartLine = 9, srcLocStartCol = 36,
 srcLocEndLine = 9, srcLocEndCol = 42})
 ("callee",SrcLoc {srcLocPackage = "main", srcLocModule = "Main",
 srcLocFile = "T.hs", srcLocStartLine = 6, srcLocStartCol = 23,
 srcLocEndLine = 6, srcLocEndCol = 29})
 }}}

 It would be nice to get the name "caller" as well.  It's too bad
 getCallStack returns pairs instead of an abstract type like Frame.
 Perhaps a separate Stack.getFrames could do that while getCallStack
 continues to return pairs for compatibility.

--
Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11686
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