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<pre><a name="line-1"></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'>Gen</span> <span class='hs-keyword'>where</span>
<a name="line-2"></a>
<a name="line-3"></a><span class='hs-comment'>--------------------------------------------------------------------------</span>
<a name="line-4"></a><span class='hs-comment'>-- imports</span>
<a name="line-5"></a>
<a name="line-6"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>System</span><span class='hs-varop'>.</span><span class='hs-conid'>Random</span>
<a name="line-7"></a> <span class='hs-layout'>(</span> <span class='hs-conid'>Random</span>
<a name="line-8"></a> <span class='hs-layout'>,</span> <span class='hs-conid'>StdGen</span>
<a name="line-9"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>randomR</span>
<a name="line-10"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>split</span>
<a name="line-11"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>newStdGen</span>
<a name="line-12"></a> <span class='hs-layout'>)</span>
<a name="line-13"></a>
<a name="line-14"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Control</span><span class='hs-varop'>.</span><span class='hs-conid'>Monad</span>
<a name="line-15"></a> <span class='hs-layout'>(</span> <span class='hs-varid'>liftM</span>
<a name="line-16"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>ap</span>
<a name="line-17"></a> <span class='hs-layout'>)</span>
<a name="line-18"></a>
<a name="line-19"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Control</span><span class='hs-varop'>.</span><span class='hs-conid'>Applicative</span>
<a name="line-20"></a> <span class='hs-layout'>(</span> <span class='hs-conid'>Applicative</span><span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span>
<a name="line-21"></a> <span class='hs-layout'>)</span>
<a name="line-22"></a>
<a name="line-23"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Control</span><span class='hs-varop'>.</span><span class='hs-conid'>Monad</span><span class='hs-varop'>.</span><span class='hs-conid'>Reader</span><span class='hs-conid'>()</span>
<a name="line-24"></a> <span class='hs-comment'>-- needed for "instance Monad (a ->)"</span>
<a name="line-25"></a>
<a name="line-26"></a> <span class='hs-comment'>-- 2005-09-16:</span>
<a name="line-27"></a> <span class='hs-comment'>-- GHC gives a warning for this. I reported this as a bug. /Koen</span>
<a name="line-28"></a>
<a name="line-29"></a><span class='hs-comment'>-- * Test case generation</span>
<a name="line-30"></a>
<a name="line-31"></a><span class='hs-comment'>--------------------------------------------------------------------------</span>
<a name="line-32"></a><span class='hs-comment'>-- ** Generator type</span>
<a name="line-33"></a>
<a name="line-34"></a><a name="Gen"></a><span class='hs-keyword'>newtype</span> <span class='hs-conid'>Gen</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>MkGen</span><span class='hs-layout'>{</span> <span class='hs-varid'>unGen</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>StdGen</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Int</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>a</span> <span class='hs-layout'>}</span>
<a name="line-35"></a>
<a name="line-36"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>Functor</span> <span class='hs-conid'>Gen</span> <span class='hs-keyword'>where</span>
<a name="line-37"></a> <span class='hs-varid'>fmap</span> <span class='hs-varid'>f</span> <span class='hs-layout'>(</span><span class='hs-conid'>MkGen</span> <span class='hs-varid'>h</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span>
<a name="line-38"></a> <span class='hs-conid'>MkGen</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span><span class='hs-varid'>r</span> <span class='hs-varid'>n</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>f</span> <span class='hs-layout'>(</span><span class='hs-varid'>h</span> <span class='hs-varid'>r</span> <span class='hs-varid'>n</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-39"></a>
<a name="line-40"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>Applicative</span> <span class='hs-conid'>Gen</span> <span class='hs-keyword'>where</span>
<a name="line-41"></a> <span class='hs-varid'>pure</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>return</span>
<a name="line-42"></a> <span class='hs-layout'>(</span><span class='hs-varop'><*></span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>ap</span>
<a name="line-43"></a>
<a name="line-44"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>Monad</span> <span class='hs-conid'>Gen</span> <span class='hs-keyword'>where</span>
<a name="line-45"></a> <span class='hs-varid'>return</span> <span class='hs-varid'>x</span> <span class='hs-keyglyph'>=</span>
<a name="line-46"></a> <span class='hs-conid'>MkGen</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span><span class='hs-keyword'>_</span> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>x</span><span class='hs-layout'>)</span>
<a name="line-47"></a>
<a name="line-48"></a> <span class='hs-conid'>MkGen</span> <span class='hs-varid'>m</span> <span class='hs-varop'>>>=</span> <span class='hs-varid'>k</span> <span class='hs-keyglyph'>=</span>
<a name="line-49"></a> <span class='hs-conid'>MkGen</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span><span class='hs-varid'>r</span> <span class='hs-varid'>n</span> <span class='hs-keyglyph'>-></span>
<a name="line-50"></a> <span class='hs-keyword'>let</span> <span class='hs-layout'>(</span><span class='hs-varid'>r1</span><span class='hs-layout'>,</span><span class='hs-varid'>r2</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>split</span> <span class='hs-varid'>r</span>
<a name="line-51"></a> <span class='hs-conid'>MkGen</span> <span class='hs-varid'>m'</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>k</span> <span class='hs-layout'>(</span><span class='hs-varid'>m</span> <span class='hs-varid'>r1</span> <span class='hs-varid'>n</span><span class='hs-layout'>)</span>
<a name="line-52"></a> <span class='hs-keyword'>in</span> <span class='hs-varid'>m'</span> <span class='hs-varid'>r2</span> <span class='hs-varid'>n</span>
<a name="line-53"></a> <span class='hs-layout'>)</span>
<a name="line-54"></a>
<a name="line-55"></a><span class='hs-comment'>--------------------------------------------------------------------------</span>
<a name="line-56"></a><span class='hs-comment'>-- ** Primitive generator combinators</span>
<a name="line-57"></a>
<a name="line-58"></a><a name="variant"></a><span class='hs-comment'>-- | Modifies a generator using an integer seed.</span>
<a name="line-59"></a><span class='hs-definition'>variant</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Integral</span> <span class='hs-varid'>n</span> <span class='hs-keyglyph'>=></span> <span class='hs-varid'>n</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Gen</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Gen</span> <span class='hs-varid'>a</span>
<a name="line-60"></a><span class='hs-definition'>variant</span> <span class='hs-varid'>k0</span> <span class='hs-layout'>(</span><span class='hs-conid'>MkGen</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>MkGen</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span><span class='hs-varid'>r</span> <span class='hs-varid'>n</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>m</span> <span class='hs-layout'>(</span><span class='hs-varid'>var</span> <span class='hs-varid'>k0</span> <span class='hs-varid'>r</span><span class='hs-layout'>)</span> <span class='hs-varid'>n</span><span class='hs-layout'>)</span>
<a name="line-61"></a> <span class='hs-keyword'>where</span>
<a name="line-62"></a> <span class='hs-varid'>var</span> <span class='hs-varid'>k</span> <span class='hs-keyglyph'>=</span> <span class='hs-layout'>(</span><span class='hs-keyword'>if</span> <span class='hs-varid'>k</span> <span class='hs-varop'>==</span> <span class='hs-varid'>k'</span> <span class='hs-keyword'>then</span> <span class='hs-varid'>id</span> <span class='hs-keyword'>else</span> <span class='hs-varid'>var</span> <span class='hs-varid'>k'</span><span class='hs-layout'>)</span>
<a name="line-63"></a> <span class='hs-varop'>.</span> <span class='hs-layout'>(</span><span class='hs-keyword'>if</span> <span class='hs-varid'>even</span> <span class='hs-varid'>k</span> <span class='hs-keyword'>then</span> <span class='hs-varid'>fst</span> <span class='hs-keyword'>else</span> <span class='hs-varid'>snd</span><span class='hs-layout'>)</span>
<a name="line-64"></a> <span class='hs-varop'>.</span> <span class='hs-varid'>split</span>
<a name="line-65"></a> <span class='hs-keyword'>where</span>
<a name="line-66"></a> <span class='hs-varid'>k'</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>k</span> <span class='hs-varop'>`div`</span> <span class='hs-num'>2</span>
<a name="line-67"></a>
<a name="line-68"></a><a name="sized"></a><span class='hs-comment'>-- | Used to construct generators that depend on the size parameter.</span>
<a name="line-69"></a><span class='hs-definition'>sized</span> <span class='hs-keyglyph'>::</span> <span class='hs-layout'>(</span><span class='hs-conid'>Int</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Gen</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Gen</span> <span class='hs-varid'>a</span>
<a name="line-70"></a><span class='hs-definition'>sized</span> <span class='hs-varid'>f</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>MkGen</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span><span class='hs-varid'>r</span> <span class='hs-varid'>n</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>let</span> <span class='hs-conid'>MkGen</span> <span class='hs-varid'>m</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>f</span> <span class='hs-varid'>n</span> <span class='hs-keyword'>in</span> <span class='hs-varid'>m</span> <span class='hs-varid'>r</span> <span class='hs-varid'>n</span><span class='hs-layout'>)</span>
<a name="line-71"></a>
<a name="line-72"></a><a name="resize"></a><span class='hs-comment'>-- | Overrides the size parameter. Returns a generator which uses</span>
<a name="line-73"></a><span class='hs-comment'>-- the given size instead of the runtime-size parameter.</span>
<a name="line-74"></a><span class='hs-definition'>resize</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Int</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Gen</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Gen</span> <span class='hs-varid'>a</span>
<a name="line-75"></a><span class='hs-definition'>resize</span> <span class='hs-varid'>n</span> <span class='hs-layout'>(</span><span class='hs-conid'>MkGen</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>MkGen</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span><span class='hs-varid'>r</span> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>m</span> <span class='hs-varid'>r</span> <span class='hs-varid'>n</span><span class='hs-layout'>)</span>
<a name="line-76"></a>
<a name="line-77"></a><a name="choose"></a><span class='hs-comment'>-- | Generates a random element in the given inclusive range.</span>
<a name="line-78"></a><span class='hs-definition'>choose</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Random</span> <span class='hs-varid'>a</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'>a</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Gen</span> <span class='hs-varid'>a</span>
<a name="line-79"></a><span class='hs-definition'>choose</span> <span class='hs-varid'>rng</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>MkGen</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span><span class='hs-varid'>r</span> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>let</span> <span class='hs-layout'>(</span><span class='hs-varid'>x</span><span class='hs-layout'>,</span><span class='hs-keyword'>_</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>randomR</span> <span class='hs-varid'>rng</span> <span class='hs-varid'>r</span> <span class='hs-keyword'>in</span> <span class='hs-varid'>x</span><span class='hs-layout'>)</span>
<a name="line-80"></a>
<a name="line-81"></a><a name="promote"></a><span class='hs-comment'>-- | Promotes a monadic generator to a generator of monadic values.</span>
<a name="line-82"></a><span class='hs-definition'>promote</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Monad</span> <span class='hs-varid'>m</span> <span class='hs-keyglyph'>=></span> <span class='hs-varid'>m</span> <span class='hs-layout'>(</span><span class='hs-conid'>Gen</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Gen</span> <span class='hs-layout'>(</span><span class='hs-varid'>m</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span>
<a name="line-83"></a><span class='hs-definition'>promote</span> <span class='hs-varid'>m</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>MkGen</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span><span class='hs-varid'>r</span> <span class='hs-varid'>n</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>liftM</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span><span class='hs-layout'>(</span><span class='hs-conid'>MkGen</span> <span class='hs-varid'>m'</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>m'</span> <span class='hs-varid'>r</span> <span class='hs-varid'>n</span><span class='hs-layout'>)</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span>
<a name="line-84"></a>
<a name="line-85"></a><a name="sample'"></a><span class='hs-comment'>-- | Generates some example values.</span>
<a name="line-86"></a><span class='hs-definition'>sample'</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Gen</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>IO</span> <span class='hs-keyglyph'>[</span><span class='hs-varid'>a</span><span class='hs-keyglyph'>]</span>
<a name="line-87"></a><span class='hs-definition'>sample'</span> <span class='hs-layout'>(</span><span class='hs-conid'>MkGen</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span>
<a name="line-88"></a> <span class='hs-keyword'>do</span> <span class='hs-varid'>rnd0</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>newStdGen</span>
<a name="line-89"></a> <span class='hs-keyword'>let</span> <span class='hs-varid'>rnds</span> <span class='hs-varid'>rnd</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>rnd1</span> <span class='hs-conop'>:</span> <span class='hs-varid'>rnds</span> <span class='hs-varid'>rnd2</span> <span class='hs-keyword'>where</span> <span class='hs-layout'>(</span><span class='hs-varid'>rnd1</span><span class='hs-layout'>,</span><span class='hs-varid'>rnd2</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>split</span> <span class='hs-varid'>rnd</span>
<a name="line-90"></a> <span class='hs-varid'>return</span> <span class='hs-keyglyph'>[</span><span class='hs-layout'>(</span><span class='hs-varid'>m</span> <span class='hs-varid'>r</span> <span class='hs-varid'>n</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>|</span> <span class='hs-layout'>(</span><span class='hs-varid'>r</span><span class='hs-layout'>,</span><span class='hs-varid'>n</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>rnds</span> <span class='hs-varid'>rnd0</span> <span class='hs-varop'>`zip`</span> <span class='hs-keyglyph'>[</span><span class='hs-num'>0</span><span class='hs-layout'>,</span><span class='hs-num'>2</span><span class='hs-keyglyph'>..</span><span class='hs-num'>20</span><span class='hs-keyglyph'>]</span> <span class='hs-keyglyph'>]</span>
<a name="line-91"></a>
<a name="line-92"></a><a name="sample"></a><span class='hs-comment'>-- | Generates some example values and prints them to 'stdout'.</span>
<a name="line-93"></a><span class='hs-definition'>sample</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Show</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>Gen</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>IO</span> <span class='hs-conid'>()</span>
<a name="line-94"></a><span class='hs-definition'>sample</span> <span class='hs-varid'>g</span> <span class='hs-keyglyph'>=</span>
<a name="line-95"></a> <span class='hs-keyword'>do</span> <span class='hs-varid'>cases</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>sample'</span> <span class='hs-varid'>g</span>
<a name="line-96"></a> <span class='hs-varid'>sequence_</span> <span class='hs-layout'>(</span><span class='hs-varid'>map</span> <span class='hs-varid'>print</span> <span class='hs-varid'>cases</span><span class='hs-layout'>)</span>
<a name="line-97"></a>
<a name="line-98"></a><span class='hs-comment'>--------------------------------------------------------------------------</span>
<a name="line-99"></a><span class='hs-comment'>-- ** Common generator combinators</span>
<a name="line-100"></a>
<a name="line-101"></a><a name="suchThat"></a><span class='hs-comment'>-- | Generates a value that satisfies a predicate.</span>
<a name="line-102"></a><span class='hs-definition'>suchThat</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Gen</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Bool</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Gen</span> <span class='hs-varid'>a</span>
<a name="line-103"></a><a name="suchThat"></a><span class='hs-definition'>gen</span> <span class='hs-varop'>`suchThat`</span> <span class='hs-varid'>p</span> <span class='hs-keyglyph'>=</span>
<a name="line-104"></a> <span class='hs-keyword'>do</span> <span class='hs-varid'>mx</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>gen</span> <span class='hs-varop'>`suchThatMaybe`</span> <span class='hs-varid'>p</span>
<a name="line-105"></a> <span class='hs-keyword'>case</span> <span class='hs-varid'>mx</span> <span class='hs-keyword'>of</span>
<a name="line-106"></a> <span class='hs-conid'>Just</span> <span class='hs-varid'>x</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-varid'>x</span>
<a name="line-107"></a> <span class='hs-conid'>Nothing</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>sized</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span><span class='hs-varid'>n</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>resize</span> <span class='hs-layout'>(</span><span class='hs-varid'>n</span><span class='hs-varop'>+</span><span class='hs-num'>1</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-varid'>gen</span> <span class='hs-varop'>`suchThat`</span> <span class='hs-varid'>p</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-108"></a>
<a name="line-109"></a><a name="suchThatMaybe"></a><span class='hs-comment'>-- | Tries to generate a value that satisfies a predicate.</span>
<a name="line-110"></a><span class='hs-definition'>suchThatMaybe</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Gen</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Bool</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Gen</span> <span class='hs-layout'>(</span><span class='hs-conid'>Maybe</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span>
<a name="line-111"></a><a name="suchThatMaybe"></a><span class='hs-definition'>gen</span> <span class='hs-varop'>`suchThatMaybe`</span> <span class='hs-varid'>p</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>sized</span> <span class='hs-layout'>(</span><span class='hs-varid'>try</span> <span class='hs-num'>0</span> <span class='hs-varop'>.</span> <span class='hs-varid'>max</span> <span class='hs-num'>1</span><span class='hs-layout'>)</span>
<a name="line-112"></a> <span class='hs-keyword'>where</span>
<a name="line-113"></a> <span class='hs-varid'>try</span> <span class='hs-keyword'>_</span> <span class='hs-num'>0</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>return</span> <span class='hs-conid'>Nothing</span>
<a name="line-114"></a> <span class='hs-varid'>try</span> <span class='hs-varid'>k</span> <span class='hs-varid'>n</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>do</span> <span class='hs-varid'>x</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>resize</span> <span class='hs-layout'>(</span><span class='hs-num'>2</span><span class='hs-varop'>*</span><span class='hs-varid'>k</span><span class='hs-varop'>+</span><span class='hs-varid'>n</span><span class='hs-layout'>)</span> <span class='hs-varid'>gen</span>
<a name="line-115"></a> <span class='hs-keyword'>if</span> <span class='hs-varid'>p</span> <span class='hs-varid'>x</span> <span class='hs-keyword'>then</span> <span class='hs-varid'>return</span> <span class='hs-layout'>(</span><span class='hs-conid'>Just</span> <span class='hs-varid'>x</span><span class='hs-layout'>)</span> <span class='hs-keyword'>else</span> <span class='hs-varid'>try</span> <span class='hs-layout'>(</span><span class='hs-varid'>k</span><span class='hs-varop'>+</span><span class='hs-num'>1</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-varid'>n</span><span class='hs-comment'>-</span><span class='hs-num'>1</span><span class='hs-layout'>)</span>
<a name="line-116"></a>
<a name="line-117"></a><a name="oneof"></a><span class='hs-comment'>-- | Randomly uses one of the given generators. The input list</span>
<a name="line-118"></a><span class='hs-comment'>-- must be non-empty.</span>
<a name="line-119"></a><span class='hs-definition'>oneof</span> <span class='hs-keyglyph'>::</span> <span class='hs-keyglyph'>[</span><span class='hs-conid'>Gen</span> <span class='hs-varid'>a</span><span class='hs-keyglyph'>]</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Gen</span> <span class='hs-varid'>a</span>
<a name="line-120"></a><span class='hs-definition'>oneof</span> <span class='hs-conid'>[]</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>error</span> <span class='hs-str'>"QuickCheck.oneof used with empty list"</span>
<a name="line-121"></a><span class='hs-definition'>oneof</span> <span class='hs-varid'>gs</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>choose</span> <span class='hs-layout'>(</span><span class='hs-num'>0</span><span class='hs-layout'>,</span><span class='hs-varid'>length</span> <span class='hs-varid'>gs</span> <span class='hs-comment'>-</span> <span class='hs-num'>1</span><span class='hs-layout'>)</span> <span class='hs-varop'>>>=</span> <span class='hs-layout'>(</span><span class='hs-varid'>gs</span> <span class='hs-varop'>!!</span><span class='hs-layout'>)</span>
<a name="line-122"></a>
<a name="line-123"></a><a name="frequency"></a><span class='hs-comment'>-- | Chooses one of the given generators, with a weighted random distribution.</span>
<a name="line-124"></a><span class='hs-comment'>-- The input list must be non-empty.</span>
<a name="line-125"></a><span class='hs-definition'>frequency</span> <span class='hs-keyglyph'>::</span> <span class='hs-keyglyph'>[</span><span class='hs-layout'>(</span><span class='hs-conid'>Int</span><span class='hs-layout'>,</span> <span class='hs-conid'>Gen</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span><span class='hs-keyglyph'>]</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Gen</span> <span class='hs-varid'>a</span>
<a name="line-126"></a><span class='hs-definition'>frequency</span> <span class='hs-conid'>[]</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>error</span> <span class='hs-str'>"QuickCheck.frequency used with empty list"</span>
<a name="line-127"></a><span class='hs-definition'>frequency</span> <span class='hs-varid'>xs0</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>choose</span> <span class='hs-layout'>(</span><span class='hs-num'>1</span><span class='hs-layout'>,</span> <span class='hs-varid'>tot</span><span class='hs-layout'>)</span> <span class='hs-varop'>>>=</span> <span class='hs-layout'>(</span><span class='hs-varop'>`pick`</span> <span class='hs-varid'>xs0</span><span class='hs-layout'>)</span>
<a name="line-128"></a> <span class='hs-keyword'>where</span>
<a name="line-129"></a> <span class='hs-varid'>tot</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>sum</span> <span class='hs-layout'>(</span><span class='hs-varid'>map</span> <span class='hs-varid'>fst</span> <span class='hs-varid'>xs0</span><span class='hs-layout'>)</span>
<a name="line-130"></a>
<a name="line-131"></a> <span class='hs-varid'>pick</span> <span class='hs-varid'>n</span> <span class='hs-layout'>(</span><span class='hs-layout'>(</span><span class='hs-varid'>k</span><span class='hs-layout'>,</span><span class='hs-varid'>x</span><span class='hs-layout'>)</span><span class='hs-conop'>:</span><span class='hs-varid'>xs</span><span class='hs-layout'>)</span>
<a name="line-132"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>n</span> <span class='hs-varop'><=</span> <span class='hs-varid'>k</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>x</span>
<a name="line-133"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>otherwise</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>pick</span> <span class='hs-layout'>(</span><span class='hs-varid'>n</span><span class='hs-comment'>-</span><span class='hs-varid'>k</span><span class='hs-layout'>)</span> <span class='hs-varid'>xs</span>
<a name="line-134"></a> <span class='hs-varid'>pick</span> <span class='hs-keyword'>_</span> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>error</span> <span class='hs-str'>"QuickCheck.pick used with empty list"</span>
<a name="line-135"></a>
<a name="line-136"></a><a name="elements"></a><span class='hs-comment'>-- | Generates one of the given values. The input list must be non-empty.</span>
<a name="line-137"></a><span class='hs-definition'>elements</span> <span class='hs-keyglyph'>::</span> <span class='hs-keyglyph'>[</span><span class='hs-varid'>a</span><span class='hs-keyglyph'>]</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Gen</span> <span class='hs-varid'>a</span>
<a name="line-138"></a><span class='hs-definition'>elements</span> <span class='hs-conid'>[]</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>error</span> <span class='hs-str'>"QuickCheck.elements used with empty list"</span>
<a name="line-139"></a><span class='hs-definition'>elements</span> <span class='hs-varid'>xs</span> <span class='hs-keyglyph'>=</span> <span class='hs-layout'>(</span><span class='hs-varid'>xs</span> <span class='hs-varop'>!!</span><span class='hs-layout'>)</span> <span class='hs-varop'>`fmap`</span> <span class='hs-varid'>choose</span> <span class='hs-layout'>(</span><span class='hs-num'>0</span><span class='hs-layout'>,</span> <span class='hs-varid'>length</span> <span class='hs-varid'>xs</span> <span class='hs-comment'>-</span> <span class='hs-num'>1</span><span class='hs-layout'>)</span>
<a name="line-140"></a>
<a name="line-141"></a><a name="growingElements"></a><span class='hs-comment'>-- | Takes a list of elements of increasing size, and chooses</span>
<a name="line-142"></a><span class='hs-comment'>-- among an initial segment of the list. The size of this initial</span>
<a name="line-143"></a><span class='hs-comment'>-- segment increases with the size parameter.</span>
<a name="line-144"></a><span class='hs-comment'>-- The input list must be non-empty.</span>
<a name="line-145"></a><span class='hs-definition'>growingElements</span> <span class='hs-keyglyph'>::</span> <span class='hs-keyglyph'>[</span><span class='hs-varid'>a</span><span class='hs-keyglyph'>]</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Gen</span> <span class='hs-varid'>a</span>
<a name="line-146"></a><span class='hs-definition'>growingElements</span> <span class='hs-conid'>[]</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>error</span> <span class='hs-str'>"QuickCheck.growingElements used with empty list"</span>
<a name="line-147"></a><span class='hs-definition'>growingElements</span> <span class='hs-varid'>xs</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>sized</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>n</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>elements</span> <span class='hs-layout'>(</span><span class='hs-varid'>take</span> <span class='hs-layout'>(</span><span class='hs-num'>1</span> <span class='hs-varop'>`max`</span> <span class='hs-varid'>size</span> <span class='hs-varid'>n</span><span class='hs-layout'>)</span> <span class='hs-varid'>xs</span><span class='hs-layout'>)</span>
<a name="line-148"></a> <span class='hs-keyword'>where</span>
<a name="line-149"></a> <span class='hs-varid'>k</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>length</span> <span class='hs-varid'>xs</span>
<a name="line-150"></a> <span class='hs-varid'>mx</span> <span class='hs-keyglyph'>=</span> <span class='hs-num'>100</span>
<a name="line-151"></a> <span class='hs-varid'>log'</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>round</span> <span class='hs-varop'>.</span> <span class='hs-varid'>log</span> <span class='hs-varop'>.</span> <span class='hs-varid'>fromIntegral</span>
<a name="line-152"></a> <span class='hs-varid'>size</span> <span class='hs-varid'>n</span> <span class='hs-keyglyph'>=</span> <span class='hs-layout'>(</span><span class='hs-varid'>log'</span> <span class='hs-varid'>n</span> <span class='hs-varop'>+</span> <span class='hs-num'>1</span><span class='hs-layout'>)</span> <span class='hs-varop'>*</span> <span class='hs-varid'>k</span> <span class='hs-varop'>`div`</span> <span class='hs-varid'>log'</span> <span class='hs-varid'>mx</span>
<a name="line-153"></a>
<a name="line-154"></a><span class='hs-comment'>{- WAS:
<a name="line-155"></a>growingElements xs = sized $ \n -> elements (take (1 `max` (n * k `div` 100)) xs)
<a name="line-156"></a> where
<a name="line-157"></a> k = length xs
<a name="line-158"></a>-}</span>
<a name="line-159"></a>
<a name="line-160"></a><a name="listOf"></a><span class='hs-comment'>-- | Generates a list of random length. The maximum length depends on the</span>
<a name="line-161"></a><span class='hs-comment'>-- size parameter.</span>
<a name="line-162"></a><span class='hs-definition'>listOf</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Gen</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Gen</span> <span class='hs-keyglyph'>[</span><span class='hs-varid'>a</span><span class='hs-keyglyph'>]</span>
<a name="line-163"></a><span class='hs-definition'>listOf</span> <span class='hs-varid'>gen</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>sized</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>n</span> <span class='hs-keyglyph'>-></span>
<a name="line-164"></a> <span class='hs-keyword'>do</span> <span class='hs-varid'>k</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>choose</span> <span class='hs-layout'>(</span><span class='hs-num'>0</span><span class='hs-layout'>,</span><span class='hs-varid'>n</span><span class='hs-layout'>)</span>
<a name="line-165"></a> <span class='hs-varid'>vectorOf</span> <span class='hs-varid'>k</span> <span class='hs-varid'>gen</span>
<a name="line-166"></a>
<a name="line-167"></a><a name="listOf1"></a><span class='hs-comment'>-- | Generates a non-empty list of random length. The maximum length </span>
<a name="line-168"></a><span class='hs-comment'>-- depends on the size parameter.</span>
<a name="line-169"></a><span class='hs-definition'>listOf1</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Gen</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Gen</span> <span class='hs-keyglyph'>[</span><span class='hs-varid'>a</span><span class='hs-keyglyph'>]</span>
<a name="line-170"></a><span class='hs-definition'>listOf1</span> <span class='hs-varid'>gen</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>sized</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>n</span> <span class='hs-keyglyph'>-></span>
<a name="line-171"></a> <span class='hs-keyword'>do</span> <span class='hs-varid'>k</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>choose</span> <span class='hs-layout'>(</span><span class='hs-num'>1</span><span class='hs-layout'>,</span><span class='hs-num'>1</span> <span class='hs-varop'>`max`</span> <span class='hs-varid'>n</span><span class='hs-layout'>)</span>
<a name="line-172"></a> <span class='hs-varid'>vectorOf</span> <span class='hs-varid'>k</span> <span class='hs-varid'>gen</span>
<a name="line-173"></a>
<a name="line-174"></a><a name="vectorOf"></a><span class='hs-comment'>-- | Generates a list of the given length.</span>
<a name="line-175"></a><span class='hs-definition'>vectorOf</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Int</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Gen</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Gen</span> <span class='hs-keyglyph'>[</span><span class='hs-varid'>a</span><span class='hs-keyglyph'>]</span>
<a name="line-176"></a><span class='hs-definition'>vectorOf</span> <span class='hs-varid'>k</span> <span class='hs-varid'>gen</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>sequence</span> <span class='hs-keyglyph'>[</span> <span class='hs-varid'>gen</span> <span class='hs-keyglyph'>|</span> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'><-</span> <span class='hs-keyglyph'>[</span><span class='hs-num'>1</span><span class='hs-keyglyph'>..</span><span class='hs-varid'>k</span><span class='hs-keyglyph'>]</span> <span class='hs-keyglyph'>]</span>
<a name="line-177"></a>
<a name="line-178"></a><span class='hs-comment'>--------------------------------------------------------------------------</span>
<a name="line-179"></a><span class='hs-comment'>-- the end.</span>
</pre></body>
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