[Haskell-cafe] Debugging

[Monang Setyawan]

Sorry, replying myself.

On 5/5/07, Monang Setyawan <monang at gmail.com> wrote:

> 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.