| Safe Haskell | Safe |
|---|---|
| Language | Haskell98 |
Agda.Utils.Function
Contents
- iterWhile :: (b -> Bool) -> (a -> (b, a)) -> a -> [(b, a)]
- repeatWhile :: (a -> (Bool, a)) -> a -> a
- repeatWhileM :: Monad m => (a -> m (Bool, a)) -> a -> m a
- trampolineWhile :: (a -> (Bool, a)) -> a -> a
- trampolineWhileM :: Monad m => (a -> m (Bool, a)) -> a -> m a
- trampoline :: (a -> Either b a) -> a -> b
- trampolineM :: Monad m => (a -> m (Either b a)) -> a -> m b
- iterateUntil :: (a -> a -> Bool) -> (a -> a) -> a -> a
- iterateUntilM :: Monad m => (a -> a -> Bool) -> (a -> m a) -> a -> m a
- iterate' :: Integral i => i -> (a -> a) -> a -> a
- applyWhen :: Bool -> (a -> a) -> a -> a
- applyUnless :: Bool -> (a -> a) -> a -> a
- applyWhenM :: Monad m => m Bool -> (m a -> m a) -> m a -> m a
- applyUnlessM :: Monad m => m Bool -> (m a -> m a) -> m a -> m a
Documentation
iterWhile :: (b -> Bool) -> (a -> (b, a)) -> a -> [(b, a)] Source
Repeat a state transition f :: a -> (b, a) with output b
while condition cond on the output is true.
Return all intermediate results and the final result
where cond is False.
Postconditions (when it terminates):
fst (last (iterWhile cond f a)) == False.
all fst (init (interWhile cond f a)).
repeatWhile :: (a -> (Bool, a)) -> a -> a Source
Repeat something while a condition on some state is true. Return the last state (including the changes of the last transition, even if the condition became false then).
repeatWhileM :: Monad m => (a -> m (Bool, a)) -> a -> m a Source
Monadic version of repeatWhile.
trampolineWhile :: (a -> (Bool, a)) -> a -> a Source
A version of the trampoline function.
The usual function iterates f :: a -> Maybe a as long
as Just{} is returned, and returns the last value of a
upon Nothing.
usualTrampoline f = trampolineWhile $ a -> maybe (False,a) (True,) (f a).
trampolineWhile is very similar to repeatWhile, only that
it discards the state on which the condition went False,
and returns the last state on which the condition was True.
trampolineWhileM :: Monad m => (a -> m (Bool, a)) -> a -> m a Source
Monadic version of trampolineWhile.
trampoline :: (a -> Either b a) -> a -> b Source
More general trampoline, which allows some final computation
from iteration state a into result type b.
trampolineM :: Monad m => (a -> m (Either b a)) -> a -> m b Source
Monadic version of trampoline.
iterateUntil :: (a -> a -> Bool) -> (a -> a) -> a -> a Source
Iteration to fixed-point.
iterateUntil r f a0 iterates endofunction f, starting with a0,
until r relates its result to its input, i.e., f a .r a
This is the generic pattern behind saturation algorithms.
If f is monotone with regard to r,
meaning a implies r bf a ,
and r f bf-chains starting with a0 are finite
then iteration is guaranteed to terminate.
A typical instance will work on sets, and r could be set inclusion,
and a0 the empty set, and f the step function of a saturation algorithm.
iterateUntilM :: Monad m => (a -> a -> Bool) -> (a -> m a) -> a -> m a Source
Monadic version of iterateUntil.
iterate' :: Integral i => i -> (a -> a) -> a -> a Source
iterate' n f xf to x n times and returns the
result.
The applications are calculated strictly.
Iteration over Booleans.
applyUnless :: Bool -> (a -> a) -> a -> a Source
applyUnless b f a applies f to a unless b.
applyWhenM :: Monad m => m Bool -> (m a -> m a) -> m a -> m a Source
Monadic version of applyWhen
applyUnlessM :: Monad m => m Bool -> (m a -> m a) -> m a -> m a Source
Monadic version of applyUnless