Copyright | (c) The University of Glasgow 2011 |
---|---|
License | see libraries/base/LICENSE |
Maintainer | cvs-ghc@haskell.org |
Stability | internal |
Portability | non-portable (GHC Extensions) |
Safe Haskell | Trustworthy |
Language | Haskell2010 |
Access to GHC's call-stack simulation
Since: 4.5.0.0
- currentCallStack :: IO [String]
- whoCreated :: a -> IO [String]
- errorWithStackTrace :: String -> a
- data CallStack
- getCallStack :: CallStack -> [(String, SrcLoc)]
- showCallStack :: CallStack -> String
- data CostCentreStack
- data CostCentre
- getCurrentCCS :: dummy -> IO (Ptr CostCentreStack)
- getCCSOf :: a -> IO (Ptr CostCentreStack)
- ccsCC :: Ptr CostCentreStack -> IO (Ptr CostCentre)
- ccsParent :: Ptr CostCentreStack -> IO (Ptr CostCentreStack)
- ccLabel :: Ptr CostCentre -> IO CString
- ccModule :: Ptr CostCentre -> IO CString
- ccSrcSpan :: Ptr CostCentre -> IO CString
- ccsToStrings :: Ptr CostCentreStack -> IO [String]
- renderStack :: [String] -> String
Call stacks
Simulated by the RTS
currentCallStack :: IO [String] Source
returns a '[String]' representing the current call stack. This can be useful for debugging.
The implementation uses the call-stack simulation maintined by the
profiler, so it only works if the program was compiled with -prof
and contains suitable SCC annotations (e.g. by using -fprof-auto
).
Otherwise, the list returned is likely to be empty or
uninformative.
Since: 4.5.0.0
whoCreated :: a -> IO [String] Source
Get the stack trace attached to an object.
Since: 4.5.0.0
errorWithStackTrace :: String -> a Source
Like the function error
, but appends a stack trace to the error
message if one is available.
Since: 4.7.0.0
Explicitly created via implicit-parameters
CallStack
s are an alternate method of obtaining the call stack at a given
point in the program.
When an implicit-parameter of type CallStack
occurs in a program, GHC will
solve it with the current location. If another CallStack
implicit-parameter
is in-scope (e.g. as a function argument), the new location will be appended
to the one in-scope, creating an explicit call-stack. For example,
myerror :: (?loc :: CallStack) => String -> a myerror msg = error (msg ++ "n" ++ showCallStack ?loc)
ghci> myerror "die" *** Exception: die ?loc, called at MyError.hs:7:51 in main:MyError myerror, called at interactive:2:1 in interactive:Ghci1
CallStack
s do not interact with the RTS and do not require compilation with
-prof
. On the other hand, as they are built up explicitly using
implicit-parameters, they will generally not contain as much information as
the simulated call-stacks maintained by the RTS.
The CallStack
type is abstract, but it can be converted into a
[(String, SrcLoc)]
via getCallStack
. The String
is the name of function
that was called, the SrcLoc
is the call-site. The list is ordered with the
most recently called function at the head.
Since: 4.9.0.0
getCallStack :: CallStack -> [(String, SrcLoc)] Source
showCallStack :: CallStack -> String Source
Internals
data CostCentreStack Source
data CostCentre Source
getCurrentCCS :: dummy -> IO (Ptr CostCentreStack) Source
getCCSOf :: a -> IO (Ptr CostCentreStack) Source
ccsCC :: Ptr CostCentreStack -> IO (Ptr CostCentre) Source
ccsParent :: Ptr CostCentreStack -> IO (Ptr CostCentreStack) Source
ccsToStrings :: Ptr CostCentreStack -> IO [String] Source
renderStack :: [String] -> String Source