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<title>Test/QuickCheck/Modifiers.hs</title>
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<pre><a name="line-1"></a><span class='hs-comment'>{-# LANGUAGE MultiParamTypeClasses, GeneralizedNewtypeDeriving #-}</span>
<a name="line-2"></a><span class='hs-keyword'>module</span> <span class='hs-conid'>Test</span><span class='hs-varop'>.</span><span class='hs-conid'>QuickCheck</span><span class='hs-varop'>.</span><span class='hs-conid'>Modifiers</span>
<a name="line-3"></a> <span class='hs-layout'>(</span>
<a name="line-4"></a> <span class='hs-comment'>-- ** Type-level modifiers for changing generator behavior</span>
<a name="line-5"></a> <span class='hs-conid'>Blind</span><span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span>
<a name="line-6"></a> <span class='hs-layout'>,</span> <span class='hs-conid'>Fixed</span><span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span>
<a name="line-7"></a> <span class='hs-layout'>,</span> <span class='hs-conid'>OrderedList</span><span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span>
<a name="line-8"></a> <span class='hs-layout'>,</span> <span class='hs-conid'>NonEmptyList</span><span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span>
<a name="line-9"></a> <span class='hs-layout'>,</span> <span class='hs-conid'>Positive</span><span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span>
<a name="line-10"></a> <span class='hs-layout'>,</span> <span class='hs-conid'>NonZero</span><span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span>
<a name="line-11"></a> <span class='hs-layout'>,</span> <span class='hs-conid'>NonNegative</span><span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span>
<a name="line-12"></a> <span class='hs-layout'>,</span> <span class='hs-conid'>Smart</span><span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span>
<a name="line-13"></a> <span class='hs-layout'>,</span> <span class='hs-conid'>Shrink2</span><span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span>
<a name="line-14"></a> <span class='hs-layout'>,</span> <span class='hs-conid'>Shrinking</span><span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span>
<a name="line-15"></a> <span class='hs-layout'>,</span> <span class='hs-conid'>ShrinkState</span><span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span>
<a name="line-16"></a> <span class='hs-layout'>)</span>
<a name="line-17"></a> <span class='hs-keyword'>where</span>
<a name="line-18"></a>
<a name="line-19"></a><span class='hs-comment'>--------------------------------------------------------------------------</span>
<a name="line-20"></a><span class='hs-comment'>-- imports</span>
<a name="line-21"></a>
<a name="line-22"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Test</span><span class='hs-varop'>.</span><span class='hs-conid'>QuickCheck</span><span class='hs-varop'>.</span><span class='hs-conid'>Gen</span>
<a name="line-23"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Test</span><span class='hs-varop'>.</span><span class='hs-conid'>QuickCheck</span><span class='hs-varop'>.</span><span class='hs-conid'>Arbitrary</span>
<a name="line-24"></a>
<a name="line-25"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>List</span>
<a name="line-26"></a> <span class='hs-layout'>(</span> <span class='hs-varid'>sort</span>
<a name="line-27"></a> <span class='hs-layout'>)</span>
<a name="line-28"></a>
<a name="line-29"></a><span class='hs-comment'>--------------------------------------------------------------------------</span>
<a name="line-30"></a><span class='hs-comment'>-- ** arbitrary modifiers</span>
<a name="line-31"></a>
<a name="line-32"></a><span class='hs-comment'>-- These datatypes are mainly here to *pattern match* on in properties.</span>
<a name="line-33"></a><span class='hs-comment'>-- This is a stylistic alternative to using explicit quantification.</span>
<a name="line-34"></a><span class='hs-comment'>-- In other words, they should not be replaced by type synonyms, and their</span>
<a name="line-35"></a><span class='hs-comment'>-- constructors should be exported.</span>
<a name="line-36"></a>
<a name="line-37"></a><span class='hs-comment'>-- Examples:</span>
<a name="line-38"></a><span class='hs-comment'>{-
<a name="line-39"></a>prop_TakeDropWhile (Blind p) (xs :: [A]) = -- because functions cannot be shown
<a name="line-40"></a> takeWhile p xs ++ dropWhile p xs == xs
<a name="line-41"></a>
<a name="line-42"></a>prop_TakeDrop (NonNegative n) (xs :: [A]) = -- (BTW, also works for negative n)
<a name="line-43"></a> take n xs ++ drop n xs == xs
<a name="line-44"></a>
<a name="line-45"></a>prop_Cycle (NonNegative n) (NonEmpty (xs :: [A])) = -- cycle does not work for empty lists
<a name="line-46"></a> take n (cycle xs) == take n (xs ++ cycle xs)
<a name="line-47"></a>
<a name="line-48"></a>prop_Sort (Ordered (xs :: [OrdA])) = -- instead of "forAll orderedList"
<a name="line-49"></a> sort xs == xs
<a name="line-50"></a>-}</span>
<a name="line-51"></a>
<a name="line-52"></a><a name="Blind"></a><span class='hs-comment'>--------------------------------------------------------------------------</span>
<a name="line-53"></a><a name="Blind"></a><span class='hs-comment'>-- | @Blind x@: as x, but x does not have to be in the 'Show' class.</span>
<a name="line-54"></a><a name="Blind"></a><span class='hs-keyword'>newtype</span> <span class='hs-conid'>Blind</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Blind</span> <span class='hs-varid'>a</span>
<a name="line-55"></a> <span class='hs-keyword'>deriving</span> <span class='hs-layout'>(</span> <span class='hs-conid'>Eq</span><span class='hs-layout'>,</span> <span class='hs-conid'>Ord</span><span class='hs-layout'>,</span> <span class='hs-conid'>Num</span><span class='hs-layout'>,</span> <span class='hs-conid'>Integral</span><span class='hs-layout'>,</span> <span class='hs-conid'>Real</span><span class='hs-layout'>,</span> <span class='hs-conid'>Enum</span> <span class='hs-layout'>)</span>
<a name="line-56"></a>
<a name="line-57"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>Show</span> <span class='hs-layout'>(</span><span class='hs-conid'>Blind</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-58"></a> <span class='hs-varid'>show</span> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'>=</span> <span class='hs-str'>"(*)"</span>
<a name="line-59"></a>
<a name="line-60"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>Arbitrary</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>Arbitrary</span> <span class='hs-layout'>(</span><span class='hs-conid'>Blind</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-61"></a> <span class='hs-varid'>arbitrary</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Blind</span> <span class='hs-varop'>`fmap`</span> <span class='hs-varid'>arbitrary</span>
<a name="line-62"></a>
<a name="line-63"></a> <span class='hs-varid'>shrink</span> <span class='hs-layout'>(</span><span class='hs-conid'>Blind</span> <span class='hs-varid'>x</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyglyph'>[</span> <span class='hs-conid'>Blind</span> <span class='hs-varid'>x'</span> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>x'</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>shrink</span> <span class='hs-varid'>x</span> <span class='hs-keyglyph'>]</span>
<a name="line-64"></a>
<a name="line-65"></a><a name="Fixed"></a><span class='hs-comment'>--------------------------------------------------------------------------</span>
<a name="line-66"></a><a name="Fixed"></a><span class='hs-comment'>-- | @Fixed x@: as x, but will not be shrunk.</span>
<a name="line-67"></a><a name="Fixed"></a><span class='hs-keyword'>newtype</span> <span class='hs-conid'>Fixed</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Fixed</span> <span class='hs-varid'>a</span>
<a name="line-68"></a> <span class='hs-keyword'>deriving</span> <span class='hs-layout'>(</span> <span class='hs-conid'>Eq</span><span class='hs-layout'>,</span> <span class='hs-conid'>Ord</span><span class='hs-layout'>,</span> <span class='hs-conid'>Num</span><span class='hs-layout'>,</span> <span class='hs-conid'>Integral</span><span class='hs-layout'>,</span> <span class='hs-conid'>Real</span><span class='hs-layout'>,</span> <span class='hs-conid'>Enum</span><span class='hs-layout'>,</span> <span class='hs-conid'>Show</span><span class='hs-layout'>,</span> <span class='hs-conid'>Read</span> <span class='hs-layout'>)</span>
<a name="line-69"></a>
<a name="line-70"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>Arbitrary</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>Arbitrary</span> <span class='hs-layout'>(</span><span class='hs-conid'>Fixed</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-71"></a> <span class='hs-varid'>arbitrary</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Fixed</span> <span class='hs-varop'>`fmap`</span> <span class='hs-varid'>arbitrary</span>
<a name="line-72"></a>
<a name="line-73"></a> <span class='hs-comment'>-- no shrink function</span>
<a name="line-74"></a>
<a name="line-75"></a><a name="OrderedList"></a><span class='hs-comment'>--------------------------------------------------------------------------</span>
<a name="line-76"></a><a name="OrderedList"></a><span class='hs-comment'>-- | @Ordered xs@: guarantees that xs is ordered.</span>
<a name="line-77"></a><a name="OrderedList"></a><span class='hs-keyword'>newtype</span> <span class='hs-conid'>OrderedList</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Ordered</span> <span class='hs-keyglyph'>[</span><span class='hs-varid'>a</span><span class='hs-keyglyph'>]</span>
<a name="line-78"></a> <span class='hs-keyword'>deriving</span> <span class='hs-layout'>(</span> <span class='hs-conid'>Eq</span><span class='hs-layout'>,</span> <span class='hs-conid'>Ord</span><span class='hs-layout'>,</span> <span class='hs-conid'>Show</span><span class='hs-layout'>,</span> <span class='hs-conid'>Read</span> <span class='hs-layout'>)</span>
<a name="line-79"></a>
<a name="line-80"></a><span class='hs-keyword'>instance</span> <span class='hs-layout'>(</span><span class='hs-conid'>Ord</span> <span class='hs-varid'>a</span><span class='hs-layout'>,</span> <span class='hs-conid'>Arbitrary</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>Arbitrary</span> <span class='hs-layout'>(</span><span class='hs-conid'>OrderedList</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-81"></a> <span class='hs-varid'>arbitrary</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Ordered</span> <span class='hs-varop'>`fmap`</span> <span class='hs-varid'>orderedList</span>
<a name="line-82"></a>
<a name="line-83"></a> <span class='hs-varid'>shrink</span> <span class='hs-layout'>(</span><span class='hs-conid'>Ordered</span> <span class='hs-varid'>xs</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span>
<a name="line-84"></a> <span class='hs-keyglyph'>[</span> <span class='hs-conid'>Ordered</span> <span class='hs-varid'>xs'</span>
<a name="line-85"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>xs'</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>shrink</span> <span class='hs-varid'>xs</span>
<a name="line-86"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>sort</span> <span class='hs-varid'>xs'</span> <span class='hs-varop'>==</span> <span class='hs-varid'>xs'</span>
<a name="line-87"></a> <span class='hs-keyglyph'>]</span>
<a name="line-88"></a>
<a name="line-89"></a><a name="NonEmptyList"></a><span class='hs-comment'>--------------------------------------------------------------------------</span>
<a name="line-90"></a><a name="NonEmptyList"></a><span class='hs-comment'>-- | @NonEmpty xs@: guarantees that xs is non-empty.</span>
<a name="line-91"></a><a name="NonEmptyList"></a><span class='hs-keyword'>newtype</span> <span class='hs-conid'>NonEmptyList</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>NonEmpty</span> <span class='hs-keyglyph'>[</span><span class='hs-varid'>a</span><span class='hs-keyglyph'>]</span>
<a name="line-92"></a> <span class='hs-keyword'>deriving</span> <span class='hs-layout'>(</span> <span class='hs-conid'>Eq</span><span class='hs-layout'>,</span> <span class='hs-conid'>Ord</span><span class='hs-layout'>,</span> <span class='hs-conid'>Show</span><span class='hs-layout'>,</span> <span class='hs-conid'>Read</span> <span class='hs-layout'>)</span>
<a name="line-93"></a>
<a name="line-94"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>Arbitrary</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>Arbitrary</span> <span class='hs-layout'>(</span><span class='hs-conid'>NonEmptyList</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-95"></a> <span class='hs-varid'>arbitrary</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>NonEmpty</span> <span class='hs-varop'>`fmap`</span> <span class='hs-layout'>(</span><span class='hs-varid'>arbitrary</span> <span class='hs-varop'>`suchThat`</span> <span class='hs-layout'>(</span><span class='hs-varid'>not</span> <span class='hs-varop'>.</span> <span class='hs-varid'>null</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-96"></a>
<a name="line-97"></a> <span class='hs-varid'>shrink</span> <span class='hs-layout'>(</span><span class='hs-conid'>NonEmpty</span> <span class='hs-varid'>xs</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span>
<a name="line-98"></a> <span class='hs-keyglyph'>[</span> <span class='hs-conid'>NonEmpty</span> <span class='hs-varid'>xs'</span>
<a name="line-99"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>xs'</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>shrink</span> <span class='hs-varid'>xs</span>
<a name="line-100"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>not</span> <span class='hs-layout'>(</span><span class='hs-varid'>null</span> <span class='hs-varid'>xs'</span><span class='hs-layout'>)</span>
<a name="line-101"></a> <span class='hs-keyglyph'>]</span>
<a name="line-102"></a>
<a name="line-103"></a><a name="Positive"></a><span class='hs-comment'>--------------------------------------------------------------------------</span>
<a name="line-104"></a><a name="Positive"></a><span class='hs-comment'>-- | @Positive x@: guarantees that @x \> 0@.</span>
<a name="line-105"></a><a name="Positive"></a><span class='hs-keyword'>newtype</span> <span class='hs-conid'>Positive</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Positive</span> <span class='hs-varid'>a</span>
<a name="line-106"></a> <span class='hs-keyword'>deriving</span> <span class='hs-layout'>(</span> <span class='hs-conid'>Eq</span><span class='hs-layout'>,</span> <span class='hs-conid'>Ord</span><span class='hs-layout'>,</span> <span class='hs-conid'>Num</span><span class='hs-layout'>,</span> <span class='hs-conid'>Integral</span><span class='hs-layout'>,</span> <span class='hs-conid'>Real</span><span class='hs-layout'>,</span> <span class='hs-conid'>Enum</span><span class='hs-layout'>,</span> <span class='hs-conid'>Show</span><span class='hs-layout'>,</span> <span class='hs-conid'>Read</span> <span class='hs-layout'>)</span>
<a name="line-107"></a>
<a name="line-108"></a><span class='hs-keyword'>instance</span> <span class='hs-layout'>(</span><span class='hs-conid'>Num</span> <span class='hs-varid'>a</span><span class='hs-layout'>,</span> <span class='hs-conid'>Ord</span> <span class='hs-varid'>a</span><span class='hs-layout'>,</span> <span class='hs-conid'>Arbitrary</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>Arbitrary</span> <span class='hs-layout'>(</span><span class='hs-conid'>Positive</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-109"></a> <span class='hs-varid'>arbitrary</span> <span class='hs-keyglyph'>=</span>
<a name="line-110"></a> <span class='hs-layout'>(</span><span class='hs-conid'>Positive</span> <span class='hs-varop'>.</span> <span class='hs-varid'>abs</span><span class='hs-layout'>)</span> <span class='hs-varop'>`fmap`</span> <span class='hs-layout'>(</span><span class='hs-varid'>arbitrary</span> <span class='hs-varop'>`suchThat`</span> <span class='hs-layout'>(</span><span class='hs-varop'>/=</span> <span class='hs-num'>0</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-111"></a>
<a name="line-112"></a> <span class='hs-varid'>shrink</span> <span class='hs-layout'>(</span><span class='hs-conid'>Positive</span> <span class='hs-varid'>x</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span>
<a name="line-113"></a> <span class='hs-keyglyph'>[</span> <span class='hs-conid'>Positive</span> <span class='hs-varid'>x'</span>
<a name="line-114"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>x'</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>shrink</span> <span class='hs-varid'>x</span>
<a name="line-115"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>x'</span> <span class='hs-varop'>></span> <span class='hs-num'>0</span>
<a name="line-116"></a> <span class='hs-keyglyph'>]</span>
<a name="line-117"></a>
<a name="line-118"></a><a name="NonZero"></a><span class='hs-comment'>--------------------------------------------------------------------------</span>
<a name="line-119"></a><a name="NonZero"></a><span class='hs-comment'>-- | @NonZero x@: guarantees that @x \/= 0@.</span>
<a name="line-120"></a><a name="NonZero"></a><span class='hs-keyword'>newtype</span> <span class='hs-conid'>NonZero</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>NonZero</span> <span class='hs-varid'>a</span>
<a name="line-121"></a> <span class='hs-keyword'>deriving</span> <span class='hs-layout'>(</span> <span class='hs-conid'>Eq</span><span class='hs-layout'>,</span> <span class='hs-conid'>Ord</span><span class='hs-layout'>,</span> <span class='hs-conid'>Num</span><span class='hs-layout'>,</span> <span class='hs-conid'>Integral</span><span class='hs-layout'>,</span> <span class='hs-conid'>Real</span><span class='hs-layout'>,</span> <span class='hs-conid'>Enum</span><span class='hs-layout'>,</span> <span class='hs-conid'>Show</span><span class='hs-layout'>,</span> <span class='hs-conid'>Read</span> <span class='hs-layout'>)</span>
<a name="line-122"></a>
<a name="line-123"></a><span class='hs-keyword'>instance</span> <span class='hs-layout'>(</span><span class='hs-conid'>Num</span> <span class='hs-varid'>a</span><span class='hs-layout'>,</span> <span class='hs-conid'>Ord</span> <span class='hs-varid'>a</span><span class='hs-layout'>,</span> <span class='hs-conid'>Arbitrary</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>Arbitrary</span> <span class='hs-layout'>(</span><span class='hs-conid'>NonZero</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-124"></a> <span class='hs-varid'>arbitrary</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>fmap</span> <span class='hs-conid'>NonZero</span> <span class='hs-varop'>$</span> <span class='hs-varid'>arbitrary</span> <span class='hs-varop'>`suchThat`</span> <span class='hs-layout'>(</span><span class='hs-varop'>/=</span> <span class='hs-num'>0</span><span class='hs-layout'>)</span>
<a name="line-125"></a>
<a name="line-126"></a> <span class='hs-varid'>shrink</span> <span class='hs-layout'>(</span><span class='hs-conid'>NonZero</span> <span class='hs-varid'>x</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyglyph'>[</span> <span class='hs-conid'>NonZero</span> <span class='hs-varid'>x'</span> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>x'</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>shrink</span> <span class='hs-varid'>x</span><span class='hs-layout'>,</span> <span class='hs-varid'>x'</span> <span class='hs-varop'>/=</span> <span class='hs-num'>0</span> <span class='hs-keyglyph'>]</span>
<a name="line-127"></a>
<a name="line-128"></a><a name="NonNegative"></a><span class='hs-comment'>--------------------------------------------------------------------------</span>
<a name="line-129"></a><a name="NonNegative"></a><span class='hs-comment'>-- | @NonNegative x@: guarantees that @x \>= 0@.</span>
<a name="line-130"></a><a name="NonNegative"></a><span class='hs-keyword'>newtype</span> <span class='hs-conid'>NonNegative</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>NonNegative</span> <span class='hs-varid'>a</span>
<a name="line-131"></a> <span class='hs-keyword'>deriving</span> <span class='hs-layout'>(</span> <span class='hs-conid'>Eq</span><span class='hs-layout'>,</span> <span class='hs-conid'>Ord</span><span class='hs-layout'>,</span> <span class='hs-conid'>Num</span><span class='hs-layout'>,</span> <span class='hs-conid'>Integral</span><span class='hs-layout'>,</span> <span class='hs-conid'>Real</span><span class='hs-layout'>,</span> <span class='hs-conid'>Enum</span><span class='hs-layout'>,</span> <span class='hs-conid'>Show</span><span class='hs-layout'>,</span> <span class='hs-conid'>Read</span> <span class='hs-layout'>)</span>
<a name="line-132"></a>
<a name="line-133"></a><span class='hs-keyword'>instance</span> <span class='hs-layout'>(</span><span class='hs-conid'>Num</span> <span class='hs-varid'>a</span><span class='hs-layout'>,</span> <span class='hs-conid'>Ord</span> <span class='hs-varid'>a</span><span class='hs-layout'>,</span> <span class='hs-conid'>Arbitrary</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>Arbitrary</span> <span class='hs-layout'>(</span><span class='hs-conid'>NonNegative</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-134"></a> <span class='hs-varid'>arbitrary</span> <span class='hs-keyglyph'>=</span>
<a name="line-135"></a> <span class='hs-varid'>frequency</span>
<a name="line-136"></a> <span class='hs-comment'>-- why is this distrbution like this?</span>
<a name="line-137"></a> <span class='hs-keyglyph'>[</span> <span class='hs-layout'>(</span><span class='hs-num'>5</span><span class='hs-layout'>,</span> <span class='hs-layout'>(</span><span class='hs-conid'>NonNegative</span> <span class='hs-varop'>.</span> <span class='hs-varid'>abs</span><span class='hs-layout'>)</span> <span class='hs-varop'>`fmap`</span> <span class='hs-varid'>arbitrary</span><span class='hs-layout'>)</span>
<a name="line-138"></a> <span class='hs-layout'>,</span> <span class='hs-layout'>(</span><span class='hs-num'>1</span><span class='hs-layout'>,</span> <span class='hs-varid'>return</span> <span class='hs-num'>0</span><span class='hs-layout'>)</span>
<a name="line-139"></a> <span class='hs-keyglyph'>]</span>
<a name="line-140"></a>
<a name="line-141"></a> <span class='hs-varid'>shrink</span> <span class='hs-layout'>(</span><span class='hs-conid'>NonNegative</span> <span class='hs-varid'>x</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span>
<a name="line-142"></a> <span class='hs-keyglyph'>[</span> <span class='hs-conid'>NonNegative</span> <span class='hs-varid'>x'</span>
<a name="line-143"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>x'</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>shrink</span> <span class='hs-varid'>x</span>
<a name="line-144"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>x'</span> <span class='hs-varop'>>=</span> <span class='hs-num'>0</span>
<a name="line-145"></a> <span class='hs-keyglyph'>]</span>
<a name="line-146"></a>
<a name="line-147"></a><a name="Shrink2"></a><span class='hs-comment'>--------------------------------------------------------------------------</span>
<a name="line-148"></a><a name="Shrink2"></a><span class='hs-comment'>-- | @Shrink2 x@: allows 2 shrinking steps at the same time when shrinking x</span>
<a name="line-149"></a><a name="Shrink2"></a><span class='hs-keyword'>newtype</span> <span class='hs-conid'>Shrink2</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Shrink2</span> <span class='hs-varid'>a</span>
<a name="line-150"></a> <span class='hs-keyword'>deriving</span> <span class='hs-layout'>(</span> <span class='hs-conid'>Eq</span><span class='hs-layout'>,</span> <span class='hs-conid'>Ord</span><span class='hs-layout'>,</span> <span class='hs-conid'>Num</span><span class='hs-layout'>,</span> <span class='hs-conid'>Integral</span><span class='hs-layout'>,</span> <span class='hs-conid'>Real</span><span class='hs-layout'>,</span> <span class='hs-conid'>Enum</span><span class='hs-layout'>,</span> <span class='hs-conid'>Show</span><span class='hs-layout'>,</span> <span class='hs-conid'>Read</span> <span class='hs-layout'>)</span>
<a name="line-151"></a>
<a name="line-152"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>Arbitrary</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>Arbitrary</span> <span class='hs-layout'>(</span><span class='hs-conid'>Shrink2</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-153"></a> <span class='hs-varid'>arbitrary</span> <span class='hs-keyglyph'>=</span>
<a name="line-154"></a> <span class='hs-conid'>Shrink2</span> <span class='hs-varop'>`fmap`</span> <span class='hs-varid'>arbitrary</span>
<a name="line-155"></a>
<a name="line-156"></a> <span class='hs-varid'>shrink</span> <span class='hs-layout'>(</span><span class='hs-conid'>Shrink2</span> <span class='hs-varid'>x</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span>
<a name="line-157"></a> <span class='hs-keyglyph'>[</span> <span class='hs-conid'>Shrink2</span> <span class='hs-varid'>y</span> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>y</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>shrink_x</span> <span class='hs-keyglyph'>]</span> <span class='hs-varop'>++</span>
<a name="line-158"></a> <span class='hs-keyglyph'>[</span> <span class='hs-conid'>Shrink2</span> <span class='hs-varid'>z</span>
<a name="line-159"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>y</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>shrink_x</span>
<a name="line-160"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>z</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>shrink</span> <span class='hs-varid'>y</span>
<a name="line-161"></a> <span class='hs-keyglyph'>]</span>
<a name="line-162"></a> <span class='hs-keyword'>where</span>
<a name="line-163"></a> <span class='hs-varid'>shrink_x</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>shrink</span> <span class='hs-varid'>x</span>
<a name="line-164"></a>
<a name="line-165"></a><a name="Smart"></a><span class='hs-comment'>--------------------------------------------------------------------------</span>
<a name="line-166"></a><a name="Smart"></a><span class='hs-comment'>-- | @Smart _ x@: tries a different order when shrinking.</span>
<a name="line-167"></a><a name="Smart"></a><span class='hs-keyword'>data</span> <span class='hs-conid'>Smart</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=</span>
<a name="line-168"></a> <span class='hs-conid'>Smart</span> <span class='hs-conid'>Int</span> <span class='hs-varid'>a</span>
<a name="line-169"></a>
<a name="line-170"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>Show</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>Show</span> <span class='hs-layout'>(</span><span class='hs-conid'>Smart</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-171"></a> <span class='hs-varid'>showsPrec</span> <span class='hs-varid'>n</span> <span class='hs-layout'>(</span><span class='hs-conid'>Smart</span> <span class='hs-keyword'>_</span> <span class='hs-varid'>x</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>showsPrec</span> <span class='hs-varid'>n</span> <span class='hs-varid'>x</span>
<a name="line-172"></a>
<a name="line-173"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>Arbitrary</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>Arbitrary</span> <span class='hs-layout'>(</span><span class='hs-conid'>Smart</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-174"></a> <span class='hs-varid'>arbitrary</span> <span class='hs-keyglyph'>=</span>
<a name="line-175"></a> <span class='hs-keyword'>do</span> <span class='hs-varid'>x</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>arbitrary</span>
<a name="line-176"></a> <span class='hs-varid'>return</span> <span class='hs-layout'>(</span><span class='hs-conid'>Smart</span> <span class='hs-num'>0</span> <span class='hs-varid'>x</span><span class='hs-layout'>)</span>
<a name="line-177"></a>
<a name="line-178"></a> <span class='hs-varid'>shrink</span> <span class='hs-layout'>(</span><span class='hs-conid'>Smart</span> <span class='hs-varid'>i</span> <span class='hs-varid'>x</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>take</span> <span class='hs-varid'>i'</span> <span class='hs-varid'>ys</span> <span class='hs-varop'>`ilv`</span> <span class='hs-varid'>drop</span> <span class='hs-varid'>i'</span> <span class='hs-varid'>ys</span>
<a name="line-179"></a> <span class='hs-keyword'>where</span>
<a name="line-180"></a> <span class='hs-varid'>ys</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyglyph'>[</span> <span class='hs-conid'>Smart</span> <span class='hs-varid'>j</span> <span class='hs-varid'>y</span> <span class='hs-keyglyph'>|</span> <span class='hs-layout'>(</span><span class='hs-varid'>j</span><span class='hs-layout'>,</span><span class='hs-varid'>y</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'><-</span> <span class='hs-keyglyph'>[</span><span class='hs-num'>0</span><span class='hs-keyglyph'>..</span><span class='hs-keyglyph'>]</span> <span class='hs-varop'>`zip`</span> <span class='hs-varid'>shrink</span> <span class='hs-varid'>x</span> <span class='hs-keyglyph'>]</span>
<a name="line-181"></a> <span class='hs-varid'>i'</span> <span class='hs-keyglyph'>=</span> <span class='hs-num'>0</span> <span class='hs-varop'>`max`</span> <span class='hs-layout'>(</span><span class='hs-varid'>i</span><span class='hs-comment'>-</span><span class='hs-num'>2</span><span class='hs-layout'>)</span>
<a name="line-182"></a>
<a name="line-183"></a> <span class='hs-conid'>[]</span> <span class='hs-varop'>`ilv`</span> <span class='hs-varid'>bs</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>bs</span>
<a name="line-184"></a> <span class='hs-keyword'>as</span> <span class='hs-varop'>`ilv`</span> <span class='hs-conid'>[]</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>as</span>
<a name="line-185"></a> <span class='hs-layout'>(</span><span class='hs-varid'>a</span><span class='hs-conop'>:</span><span class='hs-keyword'>as</span><span class='hs-layout'>)</span> <span class='hs-varop'>`ilv`</span> <span class='hs-layout'>(</span><span class='hs-varid'>b</span><span class='hs-conop'>:</span><span class='hs-varid'>bs</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>a</span> <span class='hs-conop'>:</span> <span class='hs-varid'>b</span> <span class='hs-conop'>:</span> <span class='hs-layout'>(</span><span class='hs-keyword'>as</span> <span class='hs-varop'>`ilv`</span> <span class='hs-varid'>bs</span><span class='hs-layout'>)</span>
<a name="line-186"></a>
<a name="line-187"></a><span class='hs-comment'>{-
<a name="line-188"></a> shrink (Smart i x) = part0 ++ part2 ++ part1
<a name="line-189"></a> where
<a name="line-190"></a> ys = [ Smart i y | (i,y) <- [0..] `zip` shrink x ]
<a name="line-191"></a> i' = 0 `max` (i-2)
<a name="line-192"></a> k = i `div` 10
<a name="line-193"></a>
<a name="line-194"></a> part0 = take k ys
<a name="line-195"></a> part1 = take (i'-k) (drop k ys)
<a name="line-196"></a> part2 = drop i' ys
<a name="line-197"></a>-}</span>
<a name="line-198"></a>
<a name="line-199"></a> <span class='hs-comment'>-- drop a (drop b xs) == drop (a+b) xs | a,b >= 0</span>
<a name="line-200"></a> <span class='hs-comment'>-- take a (take b xs) == take (a `min` b) xs</span>
<a name="line-201"></a> <span class='hs-comment'>-- take a xs ++ drop a xs == xs</span>
<a name="line-202"></a>
<a name="line-203"></a> <span class='hs-comment'>-- take k ys ++ take (i'-k) (drop k ys) ++ drop i' ys</span>
<a name="line-204"></a> <span class='hs-comment'>-- == take k ys ++ take (i'-k) (drop k ys) ++ drop (i'-k) (drop k ys)</span>
<a name="line-205"></a> <span class='hs-comment'>-- == take k ys ++ take (i'-k) (drop k ys) ++ drop (i'-k) (drop k ys)</span>
<a name="line-206"></a> <span class='hs-comment'>-- == take k ys ++ drop k ys</span>
<a name="line-207"></a> <span class='hs-comment'>-- == ys</span>
<a name="line-208"></a>
<a name="line-209"></a><a name="Shrinking"></a><span class='hs-comment'>--------------------------------------------------------------------------</span>
<a name="line-210"></a><a name="Shrinking"></a><span class='hs-comment'>-- | @Shrinking _ x@: allows for maintaining a state during shrinking.</span>
<a name="line-211"></a><a name="Shrinking"></a><span class='hs-keyword'>data</span> <span class='hs-conid'>Shrinking</span> <span class='hs-varid'>s</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=</span>
<a name="line-212"></a> <span class='hs-conid'>Shrinking</span> <span class='hs-varid'>s</span> <span class='hs-varid'>a</span>
<a name="line-213"></a>
<a name="line-214"></a><a name="Show"></a><span class='hs-keyword'>class</span> <span class='hs-conid'>ShrinkState</span> <span class='hs-varid'>s</span> <span class='hs-varid'>a</span> <span class='hs-keyword'>where</span>
<a name="line-215"></a> <span class='hs-varid'>shrinkInit</span> <span class='hs-keyglyph'>::</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>s</span>
<a name="line-216"></a> <span class='hs-varid'>shrinkState</span> <span class='hs-keyglyph'>::</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>s</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyglyph'>[</span><span class='hs-layout'>(</span><span class='hs-varid'>a</span><span class='hs-layout'>,</span><span class='hs-varid'>s</span><span class='hs-layout'>)</span><span class='hs-keyglyph'>]</span>
<a name="line-217"></a>
<a name="line-218"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>Show</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>Show</span> <span class='hs-layout'>(</span><span class='hs-conid'>Shrinking</span> <span class='hs-varid'>s</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-219"></a> <span class='hs-varid'>showsPrec</span> <span class='hs-varid'>n</span> <span class='hs-layout'>(</span><span class='hs-conid'>Shrinking</span> <span class='hs-keyword'>_</span> <span class='hs-varid'>x</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>showsPrec</span> <span class='hs-varid'>n</span> <span class='hs-varid'>x</span>
<a name="line-220"></a>
<a name="line-221"></a><span class='hs-keyword'>instance</span> <span class='hs-layout'>(</span><span class='hs-conid'>Arbitrary</span> <span class='hs-varid'>a</span><span class='hs-layout'>,</span> <span class='hs-conid'>ShrinkState</span> <span class='hs-varid'>s</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>Arbitrary</span> <span class='hs-layout'>(</span><span class='hs-conid'>Shrinking</span> <span class='hs-varid'>s</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-222"></a> <span class='hs-varid'>arbitrary</span> <span class='hs-keyglyph'>=</span>
<a name="line-223"></a> <span class='hs-keyword'>do</span> <span class='hs-varid'>x</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>arbitrary</span>
<a name="line-224"></a> <span class='hs-varid'>return</span> <span class='hs-layout'>(</span><span class='hs-conid'>Shrinking</span> <span class='hs-layout'>(</span><span class='hs-varid'>shrinkInit</span> <span class='hs-varid'>x</span><span class='hs-layout'>)</span> <span class='hs-varid'>x</span><span class='hs-layout'>)</span>
<a name="line-225"></a>
<a name="line-226"></a> <span class='hs-varid'>shrink</span> <span class='hs-layout'>(</span><span class='hs-conid'>Shrinking</span> <span class='hs-varid'>s</span> <span class='hs-varid'>x</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span>
<a name="line-227"></a> <span class='hs-keyglyph'>[</span> <span class='hs-conid'>Shrinking</span> <span class='hs-varid'>s'</span> <span class='hs-varid'>x'</span>
<a name="line-228"></a> <span class='hs-keyglyph'>|</span> <span class='hs-layout'>(</span><span class='hs-varid'>x'</span><span class='hs-layout'>,</span><span class='hs-varid'>s'</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>shrinkState</span> <span class='hs-varid'>x</span> <span class='hs-varid'>s</span>
<a name="line-229"></a> <span class='hs-keyglyph'>]</span>
<a name="line-230"></a>
<a name="line-231"></a><span class='hs-comment'>--------------------------------------------------------------------------</span>
<a name="line-232"></a><span class='hs-comment'>-- the end.</span>
</pre></body>
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