This package defines a MonadLoc class for monads which support Monadic Call Traces. See http:pepeiborra.posterous.com/monadic-stack-traces-that-make-a-lot-of-sense
- Traces are only provided for explicitly annotated program points.
- This package installs the MonadLoc preprocessor for this purpose. To enable it include the following pragma at the top of your haskell source files:
{ -# OPTIONS_GHC -F -pgmF MonadLoc #- }
- There is also the TH macro
withLocTH
to manually annotate program points, but you should always use the preprocessor if possible.
Documentation
class Monad m => MonadLoc m whereSource
Generating stack traces for failures
withLoc :: String -> m a -> m aSource
withLoc
records the given source location in the failure trace
if the underlying monad supports recording location traces
Monad m => MonadLoc m | |
MonadLoc m => MonadLoc (ListT m) | |
MonadLoc m => MonadLoc (ListT m) | |
(Monoid w, MonadLoc m) => MonadLoc (WriterT w m) | |
(Monoid w, MonadLoc m) => MonadLoc (WriterT w m) | |
MonadLoc m => MonadLoc (StateT s m) | |
MonadLoc m => MonadLoc (StateT s m) | |
(Error e, MonadLoc m) => MonadLoc (ErrorT e m) | |
MonadLoc m => MonadLoc (ReaderT r m) | |
(Monoid w, MonadLoc m) => MonadLoc (WriterT w m) | |
(Monoid w, MonadLoc m) => MonadLoc (WriterT w m) | |
MonadLoc m => MonadLoc (StateT s m) | |
MonadLoc m => MonadLoc (StateT s m) | |
MonadLoc m => MonadLoc (ReaderT r m) | |
(Error e, MonadLoc m) => MonadLoc (ErrorT e m) | |
(Monoid w, MonadLoc m) => MonadLoc (RWST r w s m) | |
(Monoid w, MonadLoc m) => MonadLoc (RWST r w s m) | |
(Monoid w, MonadLoc m) => MonadLoc (RWST r w s m) | |
(Monoid w, MonadLoc m) => MonadLoc (RWST r w s m) |
withLocTH
is a convenient TH macro which expands to withLoc
<source location>
It should only be used when the MonadLoc preprocessor is not available.
Usage:
f x = $withLocTH $ do $withLocTH $ something x < -$withLocTH $ something-else ...
NOTE: unfortunately type signatures are necessary when using withLocTH