| Safe Haskell | None |
|---|
Game.LambdaHack.Utils.Assert
Description
Tools for specifying assertions. A step towards contracts.
Actually, a bunch of hacks wrapping the original assert function,
which is the only easy way of obtaining source locations.
- assert :: Bool -> a -> a
- blame :: Show a => Bool -> a -> Bool
- failure :: Show a => (Bool -> b -> b) -> a -> b
- allB :: Show a => (a -> Bool) -> [a] -> Bool
- checkM :: (Show a, Monad m) => (Bool -> m () -> m ()) -> (c -> Bool) -> a -> c -> m ()
- trueM :: (Show a, Monad m) => (Bool -> m () -> m ()) -> a -> Bool -> m ()
- falseM :: (Show a, Monad m) => (Bool -> m () -> m ()) -> a -> Bool -> m ()
Documentation
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.
blame :: Show a => Bool -> a -> BoolSource
If the condition fails, display the value blamed for the failure. Used as in
assert (c /= 0 `blame` c) $ 10 / c
failure :: Show a => (Bool -> b -> b) -> a -> bSource
Like undefined, but shows the source location
and also the value to blame for the failure. To be used as in:
assert `failure` ((x1, y1), (x2, y2), "designate a vertical line")
allB :: Show a => (a -> Bool) -> [a] -> BoolSource
Like all, but if the predicate fails, blame all the list elements
and especially those for which it fails. To be used as in:
assert (allB (>= 0) [yf, xf, y1, x1, y2, x2])
checkM :: (Show a, Monad m) => (Bool -> m () -> m ()) -> (c -> Bool) -> a -> c -> m ()Source
Check that the value returned from a monad action satisfies a predicate. Reports source location and the suspects. Drops the value.