task-scheduler

This library provides resolve in Assignment.hs that can create a conflict free collection of given assignments, compliant with the respective constraints.

Algorithm

This library will implement a greeedy naive algorithm at first. Improvment of the algorithm is welcome.

Usage

To be able to use the resolvemethod from Assignment.hs the type Assignment must be instancieated.

data Assignment i c
= -- | An Assingment has:
--
-- * id = **i**
-- * constraints = **c**
AS i c

Also the i and c musst provice instances of Ord and c of Constraint from Constraints.hs.

class Constraints a where
{-# MINIMAL select, size, conflicts, (without | (\#\)) #-}
-- | Retruns the conflicting 'Constraints' of\\
-- a and b.
-- conflicts is commutative:
--
-- prop> conflicts a b = conflicts b a
conflicts :: a -> a -> a
-- | Retruns the size.\\
-- (Number of contained elements)
size :: a -> Integer
-- | Returns minimal 'Constraints'.
select :: a -> a
-- | Returns minimal 'Constraints' taking the given\\
-- ones into account. The default implementation\\
-- only takes the colliding constraints into account.\\
-- If the third argument should be taken into account\\
-- it musst be implemented.
minimize :: (Foldable f) => a -> [a] -> f a -> a
minimize a [] _ = select a
minimize a (x:xs) f = null r ? select s :? r
where r = minimize s xs f
s = a \#\ x
-- | Checks if size > 0
null :: a -> Bool
null = (==) 0 . size
-- | Removes conflicting Constrains in b from a.\\
-- Is a synonym for '\#\'
without :: a -> a -> a
without a b = a \#\ b
-- | Is a synonym for 'without'
(\#\) :: a -> a -> a
(\#\) a b = a `without` b

minimize and primarily select will be used to determine which constraints will be selected and the priority of constraints.

TODO 👀

• 📏 improve algorithm
• 📝 extend README
• ☀️ add and improve tests