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<title>src/Hint/Monad.hs</title>
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<pre><a name="line-1"></a><span class='hs-comment'>{-# LANGUAGE ViewPatterns, PatternGuards #-}</span>
<a name="line-2"></a>
<a name="line-3"></a><span class='hs-comment'>{-
<a name="line-4"></a> Find and match:
<a name="line-5"></a>
<a name="line-6"></a> mapM, foldM, forM, replicateM, sequence, zipWithM
<a name="line-7"></a> not at the last line of a do statement, or to the left of >>
<a name="line-8"></a>
<a name="line-9"></a> Use let x = y instead of x <- return y, unless x is contained
<a name="line-10"></a> within y, or bound more than once in that do block.
<a name="line-11"></a>
<a name="line-12"></a><TEST>
<a name="line-13"></a>yes = do mapM print a; return b -- mapM_ print a
<a name="line-14"></a>no = mapM print a
<a name="line-15"></a>no = do foo ; mapM print a
<a name="line-16"></a>yes = do (bar+foo) -- (bar+foo)
<a name="line-17"></a>no = do bar ; foo
<a name="line-18"></a>yes = do bar; a <- foo; return a -- do bar; foo
<a name="line-19"></a>no = do bar; a <- foo; return b
<a name="line-20"></a>yes = do x <- bar; x -- do join bar
<a name="line-21"></a>no = do x <- bar; x; x
<a name="line-22"></a>no = mdo hook <- mkTrigger pat (act >> rmHook hook) ; return hook
<a name="line-23"></a>yes = do x <- return y; foo x -- do let x = y; foo x
<a name="line-24"></a>yes = do x <- return $ y + z; foo x -- do let x = y + z; foo x
<a name="line-25"></a>no = do x <- return x; foo x
<a name="line-26"></a>no = do x <- return y; x <- return y; foo x
<a name="line-27"></a>yes = do forM files $ \x -> return (); return () -- forM_ files $ \x -> return ()
<a name="line-28"></a>yes = do if a then forM x y else sequence z q; return () -- if a then forM_ x y else sequence_ z q
<a name="line-29"></a>yes = do case a of {_ -> forM x y; x:xs -> forM x xs}; return () -- case a of _ -> forM_ x y ; x:xs -> forM_ x xs
<a name="line-30"></a></TEST>
<a name="line-31"></a>-}</span>
<a name="line-32"></a>
<a name="line-33"></a>
<a name="line-34"></a><span class='hs-keyword'>module</span> <span class='hs-conid'>Hint</span><span class='hs-varop'>.</span><span class='hs-conid'>Monad</span> <span class='hs-keyword'>where</span>
<a name="line-35"></a>
<a name="line-36"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Control</span><span class='hs-varop'>.</span><span class='hs-conid'>Arrow</span>
<a name="line-37"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>Maybe</span>
<a name="line-38"></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-39"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Hint</span><span class='hs-varop'>.</span><span class='hs-conid'>Type</span>
<a name="line-40"></a>
<a name="line-41"></a>
<a name="line-42"></a><a name="badFuncs"></a><span class='hs-definition'>badFuncs</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyglyph'>[</span><span class='hs-str'>"mapM"</span><span class='hs-layout'>,</span><span class='hs-str'>"foldM"</span><span class='hs-layout'>,</span><span class='hs-str'>"forM"</span><span class='hs-layout'>,</span><span class='hs-str'>"replicateM"</span><span class='hs-layout'>,</span><span class='hs-str'>"sequence"</span><span class='hs-layout'>,</span><span class='hs-str'>"zipWithM"</span><span class='hs-keyglyph'>]</span>
<a name="line-43"></a>
<a name="line-44"></a>
<a name="line-45"></a><a name="monadHint"></a><span class='hs-definition'>monadHint</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>DeclHint</span>
<a name="line-46"></a><span class='hs-definition'>monadHint</span> <span class='hs-keyword'>_</span> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>concatMap</span> <span class='hs-varid'>monadExp</span> <span class='hs-varop'>.</span> <span class='hs-varid'>universeBi</span>
<a name="line-47"></a>
<a name="line-48"></a><a name="monadExp"></a><span class='hs-definition'>monadExp</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Exp_</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyglyph'>[</span><span class='hs-conid'>Idea</span><span class='hs-keyglyph'>]</span>
<a name="line-49"></a><span class='hs-definition'>monadExp</span> <span class='hs-varid'>x</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>case</span> <span class='hs-varid'>x</span> <span class='hs-keyword'>of</span>
<a name="line-50"></a> <span class='hs-layout'>(</span><span class='hs-varid'>view</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>App2</span> <span class='hs-varid'>op</span> <span class='hs-varid'>x1</span> <span class='hs-varid'>x2</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>op</span> <span class='hs-varop'>~=</span> <span class='hs-str'>">>"</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>f</span> <span class='hs-varid'>x1</span>
<a name="line-51"></a> <span class='hs-conid'>Do</span> <span class='hs-keyword'>_</span> <span class='hs-varid'>xs</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyglyph'>[</span><span class='hs-varid'>err</span> <span class='hs-str'>"Redundant return"</span> <span class='hs-varid'>x</span> <span class='hs-varid'>y</span> <span class='hs-keyglyph'>|</span> <span class='hs-conid'>Just</span> <span class='hs-varid'>y</span> <span class='hs-keyglyph'><-</span> <span class='hs-keyglyph'>[</span><span class='hs-varid'>monadReturn</span> <span class='hs-varid'>xs</span><span class='hs-keyglyph'>]</span><span class='hs-keyglyph'>]</span> <span class='hs-varop'>++</span>
<a name="line-52"></a> <span class='hs-keyglyph'>[</span><span class='hs-varid'>err</span> <span class='hs-str'>"Use join"</span> <span class='hs-varid'>x</span> <span class='hs-layout'>(</span><span class='hs-conid'>Do</span> <span class='hs-varid'>an</span> <span class='hs-varid'>y</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>|</span> <span class='hs-conid'>Just</span> <span class='hs-varid'>y</span> <span class='hs-keyglyph'><-</span> <span class='hs-keyglyph'>[</span><span class='hs-varid'>monadJoin</span> <span class='hs-varid'>xs</span><span class='hs-keyglyph'>]</span><span class='hs-keyglyph'>]</span> <span class='hs-varop'>++</span>
<a name="line-53"></a> <span class='hs-keyglyph'>[</span><span class='hs-varid'>err</span> <span class='hs-str'>"Redundant do"</span> <span class='hs-varid'>x</span> <span class='hs-varid'>y</span> <span class='hs-keyglyph'>|</span> <span class='hs-keyglyph'>[</span><span class='hs-conid'>Qualifier</span> <span class='hs-keyword'>_</span> <span class='hs-varid'>y</span><span class='hs-keyglyph'>]</span> <span class='hs-keyglyph'><-</span> <span class='hs-keyglyph'>[</span><span class='hs-varid'>xs</span><span class='hs-keyglyph'>]</span><span class='hs-keyglyph'>]</span> <span class='hs-varop'>++</span>
<a name="line-54"></a> <span class='hs-keyglyph'>[</span><span class='hs-varid'>err</span> <span class='hs-str'>"Use let"</span> <span class='hs-varid'>x</span> <span class='hs-layout'>(</span><span class='hs-conid'>Do</span> <span class='hs-varid'>an</span> <span class='hs-varid'>y</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>|</span> <span class='hs-conid'>Just</span> <span class='hs-varid'>y</span> <span class='hs-keyglyph'><-</span> <span class='hs-keyglyph'>[</span><span class='hs-varid'>monadLet</span> <span class='hs-varid'>xs</span><span class='hs-keyglyph'>]</span><span class='hs-keyglyph'>]</span> <span class='hs-varop'>++</span>
<a name="line-55"></a> <span class='hs-varid'>concat</span> <span class='hs-keyglyph'>[</span><span class='hs-varid'>f</span> <span class='hs-varid'>x</span> <span class='hs-keyglyph'>|</span> <span class='hs-conid'>Qualifier</span> <span class='hs-keyword'>_</span> <span class='hs-varid'>x</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>init</span> <span class='hs-varid'>xs</span><span class='hs-keyglyph'>]</span>
<a name="line-56"></a> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>[]</span>
<a name="line-57"></a> <span class='hs-keyword'>where</span>
<a name="line-58"></a> <span class='hs-varid'>f</span> <span class='hs-varid'>x</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyglyph'>[</span><span class='hs-varid'>err</span> <span class='hs-layout'>(</span><span class='hs-str'>"Use "</span> <span class='hs-varop'>++</span> <span class='hs-varid'>name</span><span class='hs-layout'>)</span> <span class='hs-varid'>x</span> <span class='hs-varid'>y</span> <span class='hs-keyglyph'>|</span> <span class='hs-conid'>Just</span> <span class='hs-layout'>(</span><span class='hs-varid'>name</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-varid'>monadCall</span> <span class='hs-varid'>x</span><span class='hs-keyglyph'>]</span><span class='hs-keyglyph'>]</span>
<a name="line-59"></a>
<a name="line-60"></a>
<a name="line-61"></a><a name="monadCall"></a><span class='hs-comment'>-- see through Paren and down if/case etc</span>
<a name="line-62"></a><span class='hs-comment'>-- return the name to use in the hint, and the revised expression</span>
<a name="line-63"></a><span class='hs-definition'>monadCall</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Exp_</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Maybe</span> <span class='hs-layout'>(</span><span class='hs-conid'>String</span><span class='hs-layout'>,</span><span class='hs-conid'>Exp_</span><span class='hs-layout'>)</span>
<a name="line-64"></a><span class='hs-definition'>monadCall</span> <span class='hs-layout'>(</span><span class='hs-conid'>Paren</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'>fmap</span> <span class='hs-layout'>(</span><span class='hs-varid'>second</span> <span class='hs-varop'>$</span> <span class='hs-conid'>Paren</span> <span class='hs-varid'>an</span><span class='hs-layout'>)</span> <span class='hs-varop'>$</span> <span class='hs-varid'>monadCall</span> <span class='hs-varid'>x</span>
<a name="line-65"></a><span class='hs-definition'>monadCall</span> <span class='hs-layout'>(</span><span class='hs-conid'>App</span> <span class='hs-keyword'>_</span> <span class='hs-varid'>x</span> <span class='hs-varid'>y</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>fmap</span> <span class='hs-layout'>(</span><span class='hs-varid'>second</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>x</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>App</span> <span class='hs-varid'>an</span> <span class='hs-varid'>x</span> <span class='hs-varid'>y</span><span class='hs-layout'>)</span> <span class='hs-varop'>$</span> <span class='hs-varid'>monadCall</span> <span class='hs-varid'>x</span>
<a name="line-66"></a><span class='hs-definition'>monadCall</span> <span class='hs-layout'>(</span><span class='hs-conid'>InfixApp</span> <span class='hs-keyword'>_</span> <span class='hs-varid'>x</span> <span class='hs-varid'>dol</span> <span class='hs-varid'>y</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>isDol</span> <span class='hs-varid'>dol</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>fmap</span> <span class='hs-layout'>(</span><span class='hs-varid'>second</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>x</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>InfixApp</span> <span class='hs-varid'>an</span> <span class='hs-varid'>x</span> <span class='hs-varid'>dol</span> <span class='hs-varid'>y</span><span class='hs-layout'>)</span> <span class='hs-varop'>$</span> <span class='hs-varid'>monadCall</span> <span class='hs-varid'>x</span>
<a name="line-67"></a><span class='hs-definition'>monadCall</span> <span class='hs-layout'>(</span><span class='hs-varid'>replaceBranches</span> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-varid'>bs</span><span class='hs-keyglyph'>@</span><span class='hs-layout'>(</span><span class='hs-keyword'>_</span><span class='hs-conop'>:</span><span class='hs-keyword'>_</span><span class='hs-layout'>)</span><span class='hs-layout'>,</span> <span class='hs-varid'>gen</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>all</span> <span class='hs-varid'>isJust</span> <span class='hs-varid'>res</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Just</span> <span class='hs-layout'>(</span><span class='hs-varid'>fst</span> <span class='hs-varop'>$</span> <span class='hs-varid'>fromJust</span> <span class='hs-varop'>$</span> <span class='hs-varid'>head</span> <span class='hs-varid'>res</span><span class='hs-layout'>,</span> <span class='hs-varid'>gen</span> <span class='hs-varop'>$</span> <span class='hs-varid'>map</span> <span class='hs-layout'>(</span><span class='hs-varid'>snd</span> <span class='hs-varop'>.</span> <span class='hs-varid'>fromJust</span><span class='hs-layout'>)</span> <span class='hs-varid'>res</span><span class='hs-layout'>)</span>
<a name="line-68"></a> <span class='hs-keyword'>where</span> <span class='hs-varid'>res</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>map</span> <span class='hs-varid'>monadCall</span> <span class='hs-varid'>bs</span>
<a name="line-69"></a><span class='hs-definition'>monadCall</span> <span class='hs-varid'>x</span> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>x</span><span class='hs-conop'>:</span><span class='hs-keyword'>_</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>filter</span> <span class='hs-layout'>(</span><span class='hs-varid'>x</span> <span class='hs-varop'>~=</span><span class='hs-layout'>)</span> <span class='hs-varid'>badFuncs</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>let</span> <span class='hs-varid'>x2</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>x</span> <span class='hs-varop'>++</span> <span class='hs-str'>"_"</span> <span class='hs-keyword'>in</span> <span class='hs-conid'>Just</span> <span class='hs-layout'>(</span><span class='hs-varid'>x2</span><span class='hs-layout'>,</span> <span class='hs-varid'>toNamed</span> <span class='hs-varid'>x2</span><span class='hs-layout'>)</span>
<a name="line-70"></a><span class='hs-definition'>monadCall</span> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Nothing</span>
<a name="line-71"></a>
<a name="line-72"></a>
<a name="line-73"></a><a name="monadReturn"></a><span class='hs-definition'>monadReturn</span> <span class='hs-layout'>(</span><span class='hs-varid'>reverse</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Qualifier</span> <span class='hs-keyword'>_</span> <span class='hs-layout'>(</span><span class='hs-conid'>App</span> <span class='hs-keyword'>_</span> <span class='hs-varid'>ret</span> <span class='hs-layout'>(</span><span class='hs-conid'>Var</span> <span class='hs-keyword'>_</span> <span class='hs-varid'>v</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span><span class='hs-conop'>:</span><span class='hs-conid'>Generator</span> <span class='hs-keyword'>_</span> <span class='hs-layout'>(</span><span class='hs-conid'>PVar</span> <span class='hs-keyword'>_</span> <span class='hs-varid'>p</span><span class='hs-layout'>)</span> <span class='hs-varid'>x</span><span class='hs-conop'>:</span><span class='hs-varid'>rest</span><span class='hs-layout'>)</span>
<a name="line-74"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>ret</span> <span class='hs-varop'>~=</span> <span class='hs-str'>"return"</span><span class='hs-layout'>,</span> <span class='hs-varid'>fromNamed</span> <span class='hs-varid'>v</span> <span class='hs-varop'>==</span> <span class='hs-varid'>fromNamed</span> <span class='hs-varid'>p</span>
<a name="line-75"></a> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Just</span> <span class='hs-varop'>$</span> <span class='hs-conid'>Do</span> <span class='hs-varid'>an</span> <span class='hs-varop'>$</span> <span class='hs-varid'>reverse</span> <span class='hs-varop'>$</span> <span class='hs-conid'>Qualifier</span> <span class='hs-varid'>an</span> <span class='hs-varid'>x</span> <span class='hs-conop'>:</span> <span class='hs-varid'>rest</span>
<a name="line-76"></a><span class='hs-definition'>monadReturn</span> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Nothing</span>
<a name="line-77"></a>
<a name="line-78"></a>
<a name="line-79"></a><a name="monadJoin"></a><span class='hs-definition'>monadJoin</span> <span class='hs-layout'>(</span><span class='hs-conid'>Generator</span> <span class='hs-keyword'>_</span> <span class='hs-layout'>(</span><span class='hs-varid'>view</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>PVar_</span> <span class='hs-varid'>p</span><span class='hs-layout'>)</span> <span class='hs-varid'>x</span><span class='hs-conop'>:</span><span class='hs-conid'>Qualifier</span> <span class='hs-keyword'>_</span> <span class='hs-layout'>(</span><span class='hs-varid'>view</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Var_</span> <span class='hs-varid'>v</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-80"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>p</span> <span class='hs-varop'>==</span> <span class='hs-varid'>v</span> <span class='hs-varop'>&&</span> <span class='hs-varid'>v</span> <span class='hs-varop'>`notElem`</span> <span class='hs-varid'>vars</span> <span class='hs-varid'>xs</span>
<a name="line-81"></a> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Just</span> <span class='hs-varop'>$</span> <span class='hs-conid'>Qualifier</span> <span class='hs-varid'>an</span> <span class='hs-layout'>(</span><span class='hs-varid'>rebracket1</span> <span class='hs-varop'>$</span> <span class='hs-conid'>App</span> <span class='hs-varid'>an</span> <span class='hs-layout'>(</span><span class='hs-varid'>toNamed</span> <span class='hs-str'>"join"</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'>fromMaybe</span> <span class='hs-varid'>xs</span> <span class='hs-layout'>(</span><span class='hs-varid'>monadJoin</span> <span class='hs-varid'>xs</span><span class='hs-layout'>)</span>
<a name="line-82"></a><span class='hs-definition'>monadJoin</span> <span class='hs-layout'>(</span><span class='hs-varid'>x</span><span class='hs-conop'>:</span><span class='hs-varid'>xs</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>fmap</span> <span class='hs-layout'>(</span><span class='hs-varid'>x</span><span class='hs-conop'>:</span><span class='hs-layout'>)</span> <span class='hs-varop'>$</span> <span class='hs-varid'>monadJoin</span> <span class='hs-varid'>xs</span>
<a name="line-83"></a><span class='hs-definition'>monadJoin</span> <span class='hs-conid'>[]</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Nothing</span>
<a name="line-84"></a>
<a name="line-85"></a>
<a name="line-86"></a><a name="monadLet"></a><span class='hs-definition'>monadLet</span> <span class='hs-varid'>xs</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>if</span> <span class='hs-varid'>xs</span> <span class='hs-varop'>==</span> <span class='hs-varid'>ys</span> <span class='hs-keyword'>then</span> <span class='hs-conid'>Nothing</span> <span class='hs-keyword'>else</span> <span class='hs-conid'>Just</span> <span class='hs-varid'>ys</span>
<a name="line-87"></a> <span class='hs-keyword'>where</span>
<a name="line-88"></a> <span class='hs-varid'>ys</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>map</span> <span class='hs-varid'>mkLet</span> <span class='hs-varid'>xs</span>
<a name="line-89"></a> <span class='hs-varid'>vs</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>concatMap</span> <span class='hs-varid'>pvars</span> <span class='hs-keyglyph'>[</span><span class='hs-varid'>p</span> <span class='hs-keyglyph'>|</span> <span class='hs-conid'>Generator</span> <span class='hs-keyword'>_</span> <span class='hs-varid'>p</span> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>xs</span><span class='hs-keyglyph'>]</span>
<a name="line-90"></a> <span class='hs-varid'>mkLet</span> <span class='hs-layout'>(</span><span class='hs-conid'>Generator</span> <span class='hs-keyword'>_</span> <span class='hs-layout'>(</span><span class='hs-varid'>view</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>PVar_</span> <span class='hs-varid'>p</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-varid'>fromRet</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Just</span> <span class='hs-varid'>y</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-91"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>p</span> <span class='hs-varop'>`notElem`</span> <span class='hs-varid'>vars</span> <span class='hs-varid'>y</span><span class='hs-layout'>,</span> <span class='hs-varid'>p</span> <span class='hs-varop'>`notElem`</span> <span class='hs-varid'>delete</span> <span class='hs-varid'>p</span> <span class='hs-varid'>vs</span>
<a name="line-92"></a> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>LetStmt</span> <span class='hs-varid'>an</span> <span class='hs-varop'>$</span> <span class='hs-conid'>BDecls</span> <span class='hs-varid'>an</span> <span class='hs-keyglyph'>[</span><span class='hs-conid'>PatBind</span> <span class='hs-varid'>an</span> <span class='hs-layout'>(</span><span class='hs-varid'>toNamed</span> <span class='hs-varid'>p</span><span class='hs-layout'>)</span> <span class='hs-conid'>Nothing</span> <span class='hs-layout'>(</span><span class='hs-conid'>UnGuardedRhs</span> <span class='hs-varid'>an</span> <span class='hs-varid'>y</span><span class='hs-layout'>)</span> <span class='hs-conid'>Nothing</span><span class='hs-keyglyph'>]</span>
<a name="line-93"></a> <span class='hs-varid'>mkLet</span> <span class='hs-varid'>x</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>x</span>
<a name="line-94"></a>
<a name="line-95"></a><a name="fromRet"></a><span class='hs-definition'>fromRet</span> <span class='hs-layout'>(</span><span class='hs-conid'>Paren</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'>fromRet</span> <span class='hs-varid'>x</span>
<a name="line-96"></a><span class='hs-definition'>fromRet</span> <span class='hs-layout'>(</span><span class='hs-conid'>InfixApp</span> <span class='hs-keyword'>_</span> <span class='hs-varid'>x</span> <span class='hs-varid'>y</span> <span class='hs-varid'>z</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>opExp</span> <span class='hs-varid'>y</span> <span class='hs-varop'>~=</span> <span class='hs-str'>"$"</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>fromRet</span> <span class='hs-varop'>$</span> <span class='hs-conid'>App</span> <span class='hs-varid'>an</span> <span class='hs-varid'>x</span> <span class='hs-varid'>z</span>
<a name="line-97"></a><span class='hs-definition'>fromRet</span> <span class='hs-layout'>(</span><span class='hs-conid'>App</span> <span class='hs-keyword'>_</span> <span class='hs-varid'>x</span> <span class='hs-varid'>y</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>x</span> <span class='hs-varop'>~=</span> <span class='hs-str'>"return"</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Just</span> <span class='hs-varid'>y</span>
<a name="line-98"></a><span class='hs-definition'>fromRet</span> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Nothing</span>
</pre></body>
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