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<pre><a name="line-1"></a><span class='hs-comment'>{-# LANGUAGE MultiParamTypeClasses #-}</span>
<a name="line-2"></a>
<a name="line-3"></a><span class='hs-comment'>{- |
<a name="line-4"></a> /RECOMMENDATION/: Use "Data.Generics.Uniplate.Direct" instead.
<a name="line-5"></a>
<a name="line-6"></a> This module supplies a method for writing 'Biplate' instances more easily.
<a name="line-7"></a> This module requires fewest extensions, highest performance, and most instance
<a name="line-8"></a> definitions.
<a name="line-9"></a>
<a name="line-10"></a> To take an example:
<a name="line-11"></a>
<a name="line-12"></a> > data Expr = Var Int | Pos Expr String | Neg Expr | Add Expr Expr
<a name="line-13"></a> > data Stmt = Seq [Stmt] | Sel [Expr] | Let String Expr
<a name="line-14"></a> >
<a name="line-15"></a> > instance Uniplate Expr where
<a name="line-16"></a> > uniplate (Var x ) = plate Var |- x
<a name="line-17"></a> > uniplate (Pos x y) = plate Pos |* x |- y
<a name="line-18"></a> > uniplate (Neg x ) = plate Neg |* x
<a name="line-19"></a> > uniplate (Add x y) = plate Add |* x |* y
<a name="line-20"></a> >
<a name="line-21"></a> > instance Biplate Expr Expr where
<a name="line-22"></a> > biplate = plateSelf
<a name="line-23"></a> >
<a name="line-24"></a> > instance Uniplate Stmt where
<a name="line-25"></a> > uniplate (Seq x ) = plate Seq ||* x
<a name="line-26"></a> > uniplate (Sel x ) = plate Sel ||+ x
<a name="line-27"></a> > uniplate (Let x y) = plate Let |- x |- y
<a name="line-28"></a> >
<a name="line-29"></a> > instance Biplate Stmt Stmt where
<a name="line-30"></a> > biplate = plateSelf
<a name="line-31"></a> >
<a name="line-32"></a> > instance Biplate Stmt Expr where
<a name="line-33"></a> > biplate (Seq x ) = plate Seq ||+ x
<a name="line-34"></a> > biplate (Sel x ) = plate Sel ||* x
<a name="line-35"></a> > biplate (Let x y) = plate Let |- x |* y
<a name="line-36"></a>-}</span>
<a name="line-37"></a>
<a name="line-38"></a>
<a name="line-39"></a><span class='hs-keyword'>module</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>Generics</span><span class='hs-varop'>.</span><span class='hs-conid'>PlateDirect</span><span class='hs-layout'>(</span>
<a name="line-40"></a> <span class='hs-keyword'>module</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>Generics</span><span class='hs-varop'>.</span><span class='hs-conid'>Biplate</span><span class='hs-layout'>,</span>
<a name="line-41"></a> <span class='hs-comment'>-- * The Combinators</span>
<a name="line-42"></a> <span class='hs-varid'>plate</span><span class='hs-layout'>,</span> <span class='hs-varid'>plateSelf</span><span class='hs-layout'>,</span>
<a name="line-43"></a> <span class='hs-layout'>(</span><span class='hs-varop'>|+</span><span class='hs-layout'>)</span><span class='hs-layout'>,</span> <span class='hs-layout'>(</span><span class='hs-varop'>|-</span><span class='hs-layout'>)</span><span class='hs-layout'>,</span> <span class='hs-layout'>(</span><span class='hs-varop'>|*</span><span class='hs-layout'>)</span><span class='hs-layout'>,</span> <span class='hs-layout'>(</span><span class='hs-varop'>||+</span><span class='hs-layout'>)</span><span class='hs-layout'>,</span> <span class='hs-layout'>(</span><span class='hs-varop'>||*</span><span class='hs-layout'>)</span>
<a name="line-44"></a> <span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-45"></a>
<a name="line-46"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>Generics</span><span class='hs-varop'>.</span><span class='hs-conid'>Biplate</span>
<a name="line-47"></a>
<a name="line-48"></a>
<a name="line-49"></a><a name="Type"></a><span class='hs-keyword'>type</span> <span class='hs-conid'>Type</span> <span class='hs-varid'>from</span> <span class='hs-varid'>to</span> <span class='hs-keyglyph'>=</span> <span class='hs-layout'>(</span><span class='hs-conid'>Str</span> <span class='hs-varid'>to</span><span class='hs-layout'>,</span> <span class='hs-conid'>Str</span> <span class='hs-varid'>to</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>from</span><span class='hs-layout'>)</span>
<a name="line-50"></a>
<a name="line-51"></a><a name="plate"></a><span class='hs-comment'>-- | The main combinator used to start the chain.</span>
<a name="line-52"></a><span class='hs-comment'>--</span>
<a name="line-53"></a><span class='hs-comment'>-- The following rule can be used for optimisation:</span>
<a name="line-54"></a><span class='hs-comment'>--</span>
<a name="line-55"></a><span class='hs-comment'>-- > plate Ctor |- x == plate (Ctor x)</span>
<a name="line-56"></a><span class='hs-definition'>plate</span> <span class='hs-keyglyph'>::</span> <span class='hs-varid'>from</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Type</span> <span class='hs-varid'>from</span> <span class='hs-varid'>to</span>
<a name="line-57"></a><span class='hs-definition'>plate</span> <span class='hs-varid'>f</span> <span class='hs-keyglyph'>=</span> <span class='hs-layout'>(</span><span class='hs-conid'>Zero</span><span class='hs-layout'>,</span> <span class='hs-keyglyph'>\</span><span class='hs-keyword'>_</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>f</span><span class='hs-layout'>)</span>
<a name="line-58"></a>
<a name="line-59"></a>
<a name="line-60"></a><a name="|*"></a><span class='hs-comment'>-- | The field to the right is the target.</span>
<a name="line-61"></a><span class='hs-layout'>(</span><span class='hs-varop'>|*</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Type</span> <span class='hs-layout'>(</span><span class='hs-varid'>to</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>from</span><span class='hs-layout'>)</span> <span class='hs-varid'>to</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>to</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Type</span> <span class='hs-varid'>from</span> <span class='hs-varid'>to</span>
<a name="line-62"></a><span class='hs-layout'>(</span><span class='hs-varop'>|*</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-varid'>xs</span><span class='hs-layout'>,</span><span class='hs-varid'>x_</span><span class='hs-layout'>)</span> <span class='hs-varid'>y</span> <span class='hs-keyglyph'>=</span> <span class='hs-layout'>(</span><span class='hs-conid'>Two</span> <span class='hs-varid'>xs</span> <span class='hs-layout'>(</span><span class='hs-conid'>One</span> <span class='hs-varid'>y</span><span class='hs-layout'>)</span><span class='hs-layout'>,</span><span class='hs-keyglyph'>\</span><span class='hs-layout'>(</span><span class='hs-conid'>Two</span> <span class='hs-varid'>xs</span> <span class='hs-layout'>(</span><span class='hs-conid'>One</span> <span class='hs-varid'>y</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>x_</span> <span class='hs-varid'>xs</span> <span class='hs-varid'>y</span><span class='hs-layout'>)</span>
<a name="line-63"></a>
<a name="line-64"></a>
<a name="line-65"></a>
<a name="line-66"></a><a name="|+"></a><span class='hs-comment'>-- | The field to the right may contain the target.</span>
<a name="line-67"></a><span class='hs-layout'>(</span><span class='hs-varop'>|+</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Biplate</span> <span class='hs-varid'>item</span> <span class='hs-varid'>to</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>Type</span> <span class='hs-layout'>(</span><span class='hs-varid'>item</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>from</span><span class='hs-layout'>)</span> <span class='hs-varid'>to</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>item</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Type</span> <span class='hs-varid'>from</span> <span class='hs-varid'>to</span>
<a name="line-68"></a><span class='hs-layout'>(</span><span class='hs-varop'>|+</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-varid'>xs</span><span class='hs-layout'>,</span><span class='hs-varid'>x_</span><span class='hs-layout'>)</span> <span class='hs-varid'>y</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>case</span> <span class='hs-varid'>biplate</span> <span class='hs-varid'>y</span> <span class='hs-keyword'>of</span>
<a name="line-69"></a> <span class='hs-layout'>(</span><span class='hs-varid'>ys</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-layout'>(</span><span class='hs-conid'>Two</span> <span class='hs-varid'>xs</span> <span class='hs-varid'>ys</span><span class='hs-layout'>,</span> <span class='hs-keyglyph'>\</span><span class='hs-layout'>(</span><span class='hs-conid'>Two</span> <span class='hs-varid'>xs</span> <span class='hs-varid'>ys</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>x_</span> <span class='hs-varid'>xs</span> <span class='hs-layout'>(</span><span class='hs-varid'>y_</span> <span class='hs-varid'>ys</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-70"></a>
<a name="line-71"></a>
<a name="line-72"></a><a name="|-"></a><span class='hs-comment'>-- | The field to the right /does not/ contain the target.</span>
<a name="line-73"></a><span class='hs-layout'>(</span><span class='hs-varop'>|-</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Type</span> <span class='hs-layout'>(</span><span class='hs-varid'>item</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>from</span><span class='hs-layout'>)</span> <span class='hs-varid'>to</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>item</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Type</span> <span class='hs-varid'>from</span> <span class='hs-varid'>to</span>
<a name="line-74"></a><span class='hs-layout'>(</span><span class='hs-varop'>|-</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-varid'>xs</span><span class='hs-layout'>,</span><span class='hs-varid'>x_</span><span class='hs-layout'>)</span> <span class='hs-varid'>y</span> <span class='hs-keyglyph'>=</span> <span class='hs-layout'>(</span><span class='hs-varid'>xs</span><span class='hs-layout'>,</span><span class='hs-keyglyph'>\</span><span class='hs-varid'>xs</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>x_</span> <span class='hs-varid'>xs</span> <span class='hs-varid'>y</span><span class='hs-layout'>)</span>
<a name="line-75"></a>
<a name="line-76"></a>
<a name="line-77"></a><a name="||*"></a><span class='hs-comment'>-- | The field to the right is a list of the type of the target</span>
<a name="line-78"></a><span class='hs-layout'>(</span><span class='hs-varop'>||*</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Type</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>[</span><span class='hs-varid'>to</span><span class='hs-keyglyph'>]</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>from</span><span class='hs-layout'>)</span> <span class='hs-varid'>to</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyglyph'>[</span><span class='hs-varid'>to</span><span class='hs-keyglyph'>]</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Type</span> <span class='hs-varid'>from</span> <span class='hs-varid'>to</span>
<a name="line-79"></a><span class='hs-layout'>(</span><span class='hs-varop'>||*</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-varid'>xs</span><span class='hs-layout'>,</span><span class='hs-varid'>x_</span><span class='hs-layout'>)</span> <span class='hs-varid'>y</span> <span class='hs-keyglyph'>=</span> <span class='hs-layout'>(</span><span class='hs-conid'>Two</span> <span class='hs-varid'>xs</span> <span class='hs-layout'>(</span><span class='hs-varid'>listStr</span> <span class='hs-varid'>y</span><span class='hs-layout'>)</span><span class='hs-layout'>,</span> <span class='hs-keyglyph'>\</span><span class='hs-layout'>(</span><span class='hs-conid'>Two</span> <span class='hs-varid'>xs</span> <span class='hs-varid'>ys</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>x_</span> <span class='hs-varid'>xs</span> <span class='hs-layout'>(</span><span class='hs-varid'>strList</span> <span class='hs-varid'>ys</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-80"></a>
<a name="line-81"></a>
<a name="line-82"></a><a name="||+"></a><span class='hs-comment'>-- | The field to the right is a list of types which may contain the target</span>
<a name="line-83"></a><span class='hs-layout'>(</span><span class='hs-varop'>||+</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Biplate</span> <span class='hs-varid'>item</span> <span class='hs-varid'>to</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>Type</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>[</span><span class='hs-varid'>item</span><span class='hs-keyglyph'>]</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>from</span><span class='hs-layout'>)</span> <span class='hs-varid'>to</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyglyph'>[</span><span class='hs-varid'>item</span><span class='hs-keyglyph'>]</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Type</span> <span class='hs-varid'>from</span> <span class='hs-varid'>to</span>
<a name="line-84"></a><span class='hs-layout'>(</span><span class='hs-varop'>||+</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-varid'>xs</span><span class='hs-layout'>,</span><span class='hs-varid'>x_</span><span class='hs-layout'>)</span> <span class='hs-varid'>y</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>case</span> <span class='hs-varid'>plateListDiff</span> <span class='hs-varid'>y</span> <span class='hs-keyword'>of</span>
<a name="line-85"></a> <span class='hs-layout'>(</span><span class='hs-varid'>ys</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-layout'>(</span><span class='hs-conid'>Two</span> <span class='hs-varid'>xs</span> <span class='hs-varid'>ys</span><span class='hs-layout'>,</span> <span class='hs-keyglyph'>\</span><span class='hs-layout'>(</span><span class='hs-conid'>Two</span> <span class='hs-varid'>xs</span> <span class='hs-varid'>ys</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>x_</span> <span class='hs-varid'>xs</span> <span class='hs-layout'>(</span><span class='hs-varid'>y_</span> <span class='hs-varid'>ys</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-86"></a> <span class='hs-keyword'>where</span>
<a name="line-87"></a> <span class='hs-varid'>plateListDiff</span> <span class='hs-conid'>[]</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>plate</span> <span class='hs-conid'>[]</span>
<a name="line-88"></a> <span class='hs-varid'>plateListDiff</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'>plate</span> <span class='hs-layout'>(</span><span class='hs-conop'>:</span><span class='hs-layout'>)</span> <span class='hs-varop'>|+</span> <span class='hs-varid'>x</span> <span class='hs-varop'>||+</span> <span class='hs-varid'>xs</span>
<a name="line-89"></a>
<a name="line-90"></a>
<a name="line-91"></a><a name="plateSelf"></a><span class='hs-comment'>-- | Used for 'PlayAll' definitions where both types are the same.</span>
<a name="line-92"></a><span class='hs-definition'>plateSelf</span> <span class='hs-keyglyph'>::</span> <span class='hs-varid'>to</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Type</span> <span class='hs-varid'>to</span> <span class='hs-varid'>to</span>
<a name="line-93"></a><span class='hs-definition'>plateSelf</span> <span class='hs-varid'>x</span> <span class='hs-keyglyph'>=</span> <span class='hs-layout'>(</span><span class='hs-conid'>One</span> <span class='hs-varid'>x</span><span class='hs-layout'>,</span> <span class='hs-keyglyph'>\</span><span class='hs-layout'>(</span><span class='hs-conid'>One</span> <span class='hs-varid'>x</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>x</span><span class='hs-layout'>)</span>
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