Safe Haskell | None |
---|---|
Language | Haskell98 |
This module provides a variation of Dynamic
values that uses cheap
pointer equality checks to reduce the amount of signal propagation needed.
Synopsis
- data UniqDynamic t a
- uniqDynamic :: Reflex t => Dynamic t a -> UniqDynamic t a
- fromUniqDynamic :: (Reflex t, Eq a) => UniqDynamic t a -> Dynamic t a
- alreadyUniqDynamic :: Dynamic t a -> UniqDynamic t a
Documentation
data UniqDynamic t a Source #
A Dynamic
whose updated
Event
will never fire with the same value as
the current
Behavior'
s contents. In order to maintain this constraint,
the value inside a UniqDynamic
is always evaluated to
weak head normal form.
Internally, UniqDynamic
uses pointer equality as a heuristic to avoid
unnecessary update propagation; this is much more efficient than performing
full comparisons. However, when the UniqDynamic
is converted back into a
regular Dynamic
, a full comparison is performed.
Instances
uniqDynamic :: Reflex t => Dynamic t a -> UniqDynamic t a Source #
Construct a UniqDynamic
by eliminating redundant updates from a Dynamic
.
fromUniqDynamic :: (Reflex t, Eq a) => UniqDynamic t a -> Dynamic t a Source #
Retrieve a normal Dynamic
from a UniqDynamic
. This will perform a
final check using the output type's Eq
instance to ensure deterministic
behavior.
WARNING: If used with a type whose Eq
instance is not law-abiding -
specifically, if there are cases where x /= x
, fromUniqDynamic
may
eliminate more updated
occurrences than it should. For example, NaN values
of Double
and Float
are considered unequal to themselves by the Eq
instance, but can be equal by pointer equality. This may cause UniqDynamic
to lose changes from NaN to NaN.
alreadyUniqDynamic :: Dynamic t a -> UniqDynamic t a Source #
Create a UniqDynamic without uniqing it on creation. This will be slightly faster than uniqDynamic when used with a Dynamic whose values are always (or nearly always) different from its previous values; if used with a Dynamic whose values do not change frequently, it may be much slower than uniqDynamic