Sorry, replying myself.
On 5/5/07, Monang Setyawan
BTW, how about adding assertion in Haskell? Can it be done? (I've searched in my GHC 6.4.2 library documentation, and can't find 'assert')
This can be done using Assertions. Lines below are taken from the docs. Assertions assert :: Bool -> a -> a If the first argument evaluates to True, then the result is the second argument. Otherwise an AssertionFailed exception is raised, containing a String with the source file and line number of the call to assert. Assertions can normally be turned on or off with a compiler flag (for GHC, assertions are normally on unless optimisation is turned on with -O or the -fignore-asserts option is given). When assertions are turned off, the first argument to assert is ignored, and the second argument is returned as the result.