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-asserts

in your .cabal file. Otherwise, some of the functions will have no effect at all.

The library is available from [Hackage] 1 and it's homepage and issue tracker is on [github] 2. 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] 3 game engine.