assert-failure
Syntactic sugar improving 'assert' and 'error' https://github.com/Mikolaj/assert-failure
| Latest on Hackage: | 0.1.1.0 |
This package is not currently in any snapshots. If you're interested in using it, we recommend adding it to Stackage Nightly. Doing so will make builds more reliable, and allow stackage.org to host generated Haddocks.
assert-failure 
This library contains syntactic sugar that improves the usability of 'assert' and 'error'. This is actually a bunch of hacks wrapping the original 'assert' function, which is, as of GHC 7.8, the only simple way of obtaining source positions. The original 'assert' function is here re-exported for convenience.
See also http://hackage.haskell.org/package/loch, http://hackage.haskell.org/package/assert and https://ghc.haskell.org/trac/ghc/ticket/5273.
Make sure to enable assertions for your cabal package, e.g., by setting
ghc-options: -fno-ignore-assertsin your .cabal file. Otherwise, some of the functions will have no effect at all.
The library is available from Hackage and it's homepage and issue tracker is on github. The library emerged from the tons of assertions (augmented by comments and printouts) and 'error' calls (marked by unique strings to overcome their lack of source position) in the LambdaHack game engine.