Modulehedgehog-1.7Haskell2010

Hedgehog.Internal.Shrink

valuetowards :: Integral a => a -> a -> [a]

Shrink an integral number by edging towards a destination.

Example1 expression

>>> towards 0 100[0,50,75,88,94,97,99]

Example1 expression

>>> towards 500 1000[500,750,875,938,969,985,993,997,999]

Example1 expression

>>> towards (-50) (-26)[-50,-38,-32,-29,-27]

Note we always try the destination first, as that is the optimal shrink.

valuetowardsFloat :: RealFloat a => a -> a -> [a]

Shrink a floating-point number by edging towards a destination.

Example1 expression

>>> take 7 (towardsFloat 0.0 100)[0.0,50.0,75.0,87.5,93.75,96.875,98.4375]

Example1 expression

>>> take 7 (towardsFloat 1.0 0.5)[1.0,0.75,0.625,0.5625,0.53125,0.515625,0.5078125]

Note we always try the destination first, as that is the optimal shrink.

valuelist :: [a] -> [[a]]

Shrink a list by edging towards the empty list.

Example1 expression

>>> list [1,2,3][[],[2,3],[1,3],[1,2]]

Example1 expression

>>> list "abcd"["","cd","ab","bcd","acd","abd","abc"]

Note we always try the empty list first, as that is the optimal shrink.

valuehalves :: Integral a => a -> [a]

Produce a list containing the progressive halving of an integral.

Example1 expression

>>> halves 15[15,7,3,1]

Example1 expression

>>> halves 100[100,50,25,12,6,3,1]

Example1 expression

>>> halves (-26)[-26,-13,-6,-3,-1]

valueremoves :: Int -> [a] -> [[a]]

Produce all permutations of removing k elements from a list.

Example1 expression

>>> removes 2 "abcdef"["cdef","abef","abcd"]

valueconsNub :: Eq a => a -> [a] -> [a]

Cons an element on to the front of a list unless it is already there.