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<pre><a name="line-1"></a><span class='hs-comment'>{-| Element-agnostic grouping utilities for @pipes@
<a name="line-2"></a>
<a name="line-3"></a> See "Pipes.Group.Tutorial" for an extended tutorial
<a name="line-4"></a>-}</span>
<a name="line-5"></a>
<a name="line-6"></a><span class='hs-comment'>{-# LANGUAGE RankNTypes #-}</span>
<a name="line-7"></a>
<a name="line-8"></a><span class='hs-keyword'>module</span> <span class='hs-conid'>Pipes</span><span class='hs-varop'>.</span><span class='hs-conid'>Group</span> <span class='hs-layout'>(</span>
<a name="line-9"></a> <span class='hs-comment'>-- * Lenses</span>
<a name="line-10"></a> <span class='hs-varid'>groupsBy</span><span class='hs-layout'>,</span>
<a name="line-11"></a> <span class='hs-varid'>groupsBy'</span><span class='hs-layout'>,</span>
<a name="line-12"></a> <span class='hs-varid'>groups</span><span class='hs-layout'>,</span>
<a name="line-13"></a> <span class='hs-varid'>chunksOf</span><span class='hs-layout'>,</span>
<a name="line-14"></a>
<a name="line-15"></a> <span class='hs-comment'>-- * Transformations</span>
<a name="line-16"></a> <span class='hs-varid'>takes</span><span class='hs-layout'>,</span>
<a name="line-17"></a> <span class='hs-varid'>takes'</span><span class='hs-layout'>,</span>
<a name="line-18"></a> <span class='hs-varid'>drops</span><span class='hs-layout'>,</span>
<a name="line-19"></a> <span class='hs-varid'>maps</span><span class='hs-layout'>,</span>
<a name="line-20"></a> <span class='hs-varid'>individually</span><span class='hs-layout'>,</span>
<a name="line-21"></a>
<a name="line-22"></a> <span class='hs-comment'>-- * Joiners</span>
<a name="line-23"></a> <span class='hs-varid'>concats</span><span class='hs-layout'>,</span>
<a name="line-24"></a> <span class='hs-varid'>intercalates</span><span class='hs-layout'>,</span>
<a name="line-25"></a>
<a name="line-26"></a> <span class='hs-comment'>-- * Folds</span>
<a name="line-27"></a> <span class='hs-comment'>-- $folds</span>
<a name="line-28"></a> <span class='hs-varid'>folds</span><span class='hs-layout'>,</span>
<a name="line-29"></a> <span class='hs-varid'>foldsM</span><span class='hs-layout'>,</span>
<a name="line-30"></a>
<a name="line-31"></a> <span class='hs-comment'>-- * Re-exports</span>
<a name="line-32"></a> <span class='hs-comment'>-- $reexports</span>
<a name="line-33"></a> <span class='hs-keyword'>module</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'>Trans</span><span class='hs-varop'>.</span><span class='hs-conid'>Class</span><span class='hs-layout'>,</span>
<a name="line-34"></a> <span class='hs-keyword'>module</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'>Trans</span><span class='hs-varop'>.</span><span class='hs-conid'>Free</span><span class='hs-layout'>,</span>
<a name="line-35"></a> <span class='hs-keyword'>module</span> <span class='hs-conid'>Pipes</span>
<a name="line-36"></a> <span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-37"></a>
<a name="line-38"></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'>Trans</span><span class='hs-varop'>.</span><span class='hs-conid'>Class</span> <span class='hs-layout'>(</span><span class='hs-varid'>lift</span><span class='hs-layout'>)</span>
<a name="line-39"></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'>Trans</span><span class='hs-varop'>.</span><span class='hs-conid'>Free</span> <span class='hs-layout'>(</span><span class='hs-conid'>FreeF</span><span class='hs-layout'>(</span><span class='hs-conid'>Pure</span><span class='hs-layout'>,</span> <span class='hs-conid'>Free</span><span class='hs-layout'>)</span><span class='hs-layout'>,</span> <span class='hs-conid'>FreeT</span><span class='hs-layout'>(</span><span class='hs-conid'>FreeT</span><span class='hs-layout'>,</span> <span class='hs-varid'>runFreeT</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-40"></a><span class='hs-keyword'>import</span> <span class='hs-keyword'>qualified</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'>Trans</span><span class='hs-varop'>.</span><span class='hs-conid'>Free</span> <span class='hs-keyword'>as</span> <span class='hs-conid'>F</span>
<a name="line-41"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>Functor</span><span class='hs-varop'>.</span><span class='hs-conid'>Constant</span> <span class='hs-layout'>(</span><span class='hs-conid'>Constant</span><span class='hs-layout'>(</span><span class='hs-conid'>Constant</span><span class='hs-layout'>,</span> <span class='hs-varid'>getConstant</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-42"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>Functor</span><span class='hs-varop'>.</span><span class='hs-conid'>Identity</span> <span class='hs-layout'>(</span><span class='hs-conid'>Identity</span><span class='hs-layout'>(</span><span class='hs-conid'>Identity</span><span class='hs-layout'>,</span> <span class='hs-varid'>runIdentity</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-43"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Pipes</span> <span class='hs-layout'>(</span><span class='hs-conid'>Producer</span><span class='hs-layout'>,</span> <span class='hs-varid'>yield</span><span class='hs-layout'>,</span> <span class='hs-varid'>next</span><span class='hs-layout'>)</span>
<a name="line-44"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Pipes</span><span class='hs-varop'>.</span><span class='hs-conid'>Parse</span> <span class='hs-layout'>(</span><span class='hs-varid'>span</span><span class='hs-layout'>,</span> <span class='hs-varid'>splitAt</span><span class='hs-layout'>)</span>
<a name="line-45"></a><span class='hs-keyword'>import</span> <span class='hs-keyword'>qualified</span> <span class='hs-conid'>Pipes</span> <span class='hs-keyword'>as</span> <span class='hs-conid'>P</span>
<a name="line-46"></a>
<a name="line-47"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Prelude</span> <span class='hs-varid'>hiding</span> <span class='hs-layout'>(</span><span class='hs-varid'>span</span><span class='hs-layout'>,</span> <span class='hs-varid'>splitAt</span><span class='hs-layout'>)</span>
<a name="line-48"></a>
<a name="line-49"></a><a name="Lens"></a><span class='hs-keyword'>type</span> <span class='hs-conid'>Lens</span> <span class='hs-varid'>a'</span> <span class='hs-varid'>a</span> <span class='hs-varid'>b'</span> <span class='hs-varid'>b</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>forall</span> <span class='hs-varid'>f</span> <span class='hs-varop'>.</span> <span class='hs-conid'>Functor</span> <span class='hs-varid'>f</span> <span class='hs-keyglyph'>=></span> <span class='hs-layout'>(</span><span class='hs-varid'>b'</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>f</span> <span class='hs-varid'>b</span><span class='hs-layout'>)</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-varid'>f</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span>
<a name="line-50"></a><a name="Setter"></a><span class='hs-keyword'>type</span> <span class='hs-conid'>Setter</span> <span class='hs-varid'>a'</span> <span class='hs-varid'>a</span> <span class='hs-varid'>b'</span> <span class='hs-varid'>b</span> <span class='hs-keyglyph'>=</span> <span class='hs-layout'>(</span><span class='hs-varid'>b'</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Identity</span> <span class='hs-varid'>b</span><span class='hs-layout'>)</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'>Identity</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span>
<a name="line-51"></a>
<a name="line-52"></a><a name="%5e."></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'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-layout'>(</span><span class='hs-varid'>b</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Constant</span> <span class='hs-varid'>b</span> <span class='hs-varid'>b</span><span class='hs-layout'>)</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'>Constant</span> <span class='hs-varid'>b</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>b</span>
<a name="line-53"></a><a name="a"></a><span class='hs-definition'>a</span> <span class='hs-varop'>^.</span> <span class='hs-varid'>lens</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>getConstant</span> <span class='hs-layout'>(</span><span class='hs-varid'>lens</span> <span class='hs-conid'>Constant</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span>
<a name="line-54"></a>
<a name="line-55"></a><a name="groupsBy"></a><span class='hs-comment'>{-| 'groupsBy' splits a 'Producer' into a 'FreeT' of 'Producer's grouped using
<a name="line-56"></a> the given equality predicate
<a name="line-57"></a>
<a name="line-58"></a>>>> import Lens.Family (view)
<a name="line-59"></a>>>> import Pipes (yield, each)
<a name="line-60"></a>>>> import Pipes.Prelude (toList)
<a name="line-61"></a>>>> (toList . intercalates (yield '|') . view (groupsBy (==))) (each "12233345")
<a name="line-62"></a>"1|22|333|4|5"
<a name="line-63"></a>
<a name="line-64"></a> You can think of this as:
<a name="line-65"></a>
<a name="line-66"></a>> groupsBy
<a name="line-67"></a>> :: Monad m
<a name="line-68"></a>> => (a -> a -> Bool) -> Lens' (Producer a m x) (FreeT (Producer a m) m x)
<a name="line-69"></a>-}</span>
<a name="line-70"></a><span class='hs-definition'>groupsBy</span>
<a name="line-71"></a> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Monad</span> <span class='hs-varid'>m</span>
<a name="line-72"></a> <span class='hs-keyglyph'>=></span> <span class='hs-layout'>(</span><span class='hs-varid'>a'</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>a'</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Bool</span><span class='hs-layout'>)</span>
<a name="line-73"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Lens</span> <span class='hs-layout'>(</span><span class='hs-conid'>Producer</span> <span class='hs-varid'>a'</span> <span class='hs-varid'>m</span> <span class='hs-varid'>x</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-conid'>Producer</span> <span class='hs-varid'>a</span> <span class='hs-varid'>m</span> <span class='hs-varid'>x</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-conid'>FreeT</span> <span class='hs-layout'>(</span><span class='hs-conid'>Producer</span> <span class='hs-varid'>a'</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-varid'>m</span> <span class='hs-varid'>x</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-conid'>FreeT</span> <span class='hs-layout'>(</span><span class='hs-conid'>Producer</span> <span class='hs-varid'>a</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-varid'>m</span> <span class='hs-varid'>x</span><span class='hs-layout'>)</span>
<a name="line-74"></a><span class='hs-definition'>groupsBy</span> <span class='hs-varid'>equals</span> <span class='hs-varid'>k</span> <span class='hs-varid'>p0</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>fmap</span> <span class='hs-varid'>concats</span> <span class='hs-layout'>(</span><span class='hs-varid'>k</span> <span class='hs-layout'>(</span><span class='hs-sel'>_groupsBy</span> <span class='hs-varid'>p0</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-75"></a> <span class='hs-keyword'>where</span>
<a name="line-76"></a><span class='hs-comment'>-- _groupsBy :: Monad m => Producer a m r -> FreeT (Producer a m) m r</span>
<a name="line-77"></a> <span class='hs-sel'>_groupsBy</span> <span class='hs-varid'>p</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>FreeT</span> <span class='hs-varop'>$</span> <span class='hs-keyword'>do</span>
<a name="line-78"></a> <span class='hs-varid'>x</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>next</span> <span class='hs-varid'>p</span>
<a name="line-79"></a> <span class='hs-varid'>return</span> <span class='hs-varop'>$</span> <span class='hs-keyword'>case</span> <span class='hs-varid'>x</span> <span class='hs-keyword'>of</span>
<a name="line-80"></a> <span class='hs-conid'>Left</span> <span class='hs-varid'>r</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Pure</span> <span class='hs-varid'>r</span>
<a name="line-81"></a> <span class='hs-conid'>Right</span> <span class='hs-layout'>(</span><span class='hs-varid'>a</span><span class='hs-layout'>,</span> <span class='hs-varid'>p'</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Free</span> <span class='hs-varop'>$</span>
<a name="line-82"></a> <span class='hs-varid'>fmap</span> <span class='hs-sel'>_groupsBy</span> <span class='hs-layout'>(</span><span class='hs-varid'>yield</span> <span class='hs-varid'>a</span> <span class='hs-varop'>>></span> <span class='hs-layout'>(</span><span class='hs-varid'>p'</span> <span class='hs-varop'>^.</span> <span class='hs-varid'>span</span> <span class='hs-layout'>(</span><span class='hs-varid'>equals</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-83"></a><span class='hs-comment'>{-# INLINABLE groupsBy #-}</span>
<a name="line-84"></a>
<a name="line-85"></a><a name="groupsBy'"></a><span class='hs-comment'>{-| `groupsBy'` splits a 'Producer' into a 'FreeT' of 'Producer's grouped using
<a name="line-86"></a> the given equality predicate
<a name="line-87"></a>
<a name="line-88"></a> This differs from `groupsBy` by comparing successive elements for equality
<a name="line-89"></a> instead of comparing each element to the first member of the group
<a name="line-90"></a>
<a name="line-91"></a>>>> import Lens.Family (view)
<a name="line-92"></a>>>> import Pipes (yield, each)
<a name="line-93"></a>>>> import Pipes.Prelude (toList)
<a name="line-94"></a>>>> let cmp c1 c2 = succ c1 == c2
<a name="line-95"></a>>>> (toList . intercalates (yield '|') . view (groupsBy' cmp)) (each "12233345")
<a name="line-96"></a>"12|23|3|345"
<a name="line-97"></a>>>> (toList . intercalates (yield '|') . view (groupsBy cmp)) (each "12233345")
<a name="line-98"></a>"122|3|3|34|5"
<a name="line-99"></a>
<a name="line-100"></a> You can think of this as:
<a name="line-101"></a>
<a name="line-102"></a>> groupsBy'
<a name="line-103"></a>> :: Monad m
<a name="line-104"></a>> => (a -> a -> Bool)
<a name="line-105"></a>> -> Lens' (Producer a m x) (FreeT (Producer a m) m x)
<a name="line-106"></a>-}</span>
<a name="line-107"></a><span class='hs-definition'>groupsBy'</span>
<a name="line-108"></a> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Monad</span> <span class='hs-varid'>m</span>
<a name="line-109"></a> <span class='hs-keyglyph'>=></span> <span class='hs-layout'>(</span><span class='hs-varid'>a'</span> <span class='hs-keyglyph'>-></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'>Lens</span> <span class='hs-layout'>(</span><span class='hs-conid'>Producer</span> <span class='hs-varid'>a'</span> <span class='hs-varid'>m</span> <span class='hs-varid'>x</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-conid'>Producer</span> <span class='hs-varid'>a</span> <span class='hs-varid'>m</span> <span class='hs-varid'>x</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-conid'>FreeT</span> <span class='hs-layout'>(</span><span class='hs-conid'>Producer</span> <span class='hs-varid'>a'</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-varid'>m</span> <span class='hs-varid'>x</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-conid'>FreeT</span> <span class='hs-layout'>(</span><span class='hs-conid'>Producer</span> <span class='hs-varid'>a</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-varid'>m</span> <span class='hs-varid'>x</span><span class='hs-layout'>)</span>
<a name="line-110"></a><span class='hs-definition'>groupsBy'</span> <span class='hs-varid'>equals</span> <span class='hs-varid'>k</span> <span class='hs-varid'>p0</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>fmap</span> <span class='hs-varid'>concats</span> <span class='hs-layout'>(</span><span class='hs-varid'>k</span> <span class='hs-layout'>(</span><span class='hs-sel'>_groupsBy</span> <span class='hs-varid'>p0</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-111"></a> <span class='hs-keyword'>where</span>
<a name="line-112"></a><span class='hs-comment'>-- _groupsBy :: Monad m => Producer a m r -> FreeT (Producer a m) m r</span>
<a name="line-113"></a> <span class='hs-sel'>_groupsBy</span> <span class='hs-varid'>p</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>FreeT</span> <span class='hs-varop'>$</span> <span class='hs-keyword'>do</span>
<a name="line-114"></a> <span class='hs-varid'>x</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>next</span> <span class='hs-varid'>p</span>
<a name="line-115"></a> <span class='hs-varid'>return</span> <span class='hs-varop'>$</span> <span class='hs-keyword'>case</span> <span class='hs-varid'>x</span> <span class='hs-keyword'>of</span>
<a name="line-116"></a> <span class='hs-conid'>Left</span> <span class='hs-varid'>r</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Pure</span> <span class='hs-varid'>r</span>
<a name="line-117"></a> <span class='hs-conid'>Right</span> <span class='hs-layout'>(</span><span class='hs-varid'>a</span><span class='hs-layout'>,</span> <span class='hs-varid'>p'</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Free</span> <span class='hs-layout'>(</span><span class='hs-varid'>fmap</span> <span class='hs-sel'>_groupsBy</span> <span class='hs-layout'>(</span><span class='hs-varid'>loop0</span> <span class='hs-layout'>(</span><span class='hs-varid'>yield</span> <span class='hs-varid'>a</span> <span class='hs-varop'>>></span> <span class='hs-varid'>p'</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-118"></a>
<a name="line-119"></a><span class='hs-comment'>-- loop0</span>
<a name="line-120"></a><span class='hs-comment'>-- :: Monad m</span>
<a name="line-121"></a><span class='hs-comment'>-- => Producer a m r</span>
<a name="line-122"></a><span class='hs-comment'>-- -> Producer a m (Producer a m r)</span>
<a name="line-123"></a> <span class='hs-varid'>loop0</span> <span class='hs-varid'>p1</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>do</span>
<a name="line-124"></a> <span class='hs-varid'>x</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>lift</span> <span class='hs-layout'>(</span><span class='hs-varid'>next</span> <span class='hs-varid'>p1</span><span class='hs-layout'>)</span>
<a name="line-125"></a> <span class='hs-keyword'>case</span> <span class='hs-varid'>x</span> <span class='hs-keyword'>of</span>
<a name="line-126"></a> <span class='hs-conid'>Left</span> <span class='hs-varid'>r</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-layout'>(</span><span class='hs-varid'>return</span> <span class='hs-varid'>r</span><span class='hs-layout'>)</span>
<a name="line-127"></a> <span class='hs-conid'>Right</span> <span class='hs-layout'>(</span><span class='hs-varid'>a2</span><span class='hs-layout'>,</span> <span class='hs-varid'>p2</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>do</span>
<a name="line-128"></a> <span class='hs-varid'>yield</span> <span class='hs-varid'>a2</span>
<a name="line-129"></a> <span class='hs-keyword'>let</span> <span class='hs-varid'>loop1</span> <span class='hs-varid'>a</span> <span class='hs-varid'>p</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>do</span>
<a name="line-130"></a> <span class='hs-varid'>y</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>lift</span> <span class='hs-layout'>(</span><span class='hs-varid'>next</span> <span class='hs-varid'>p</span><span class='hs-layout'>)</span>
<a name="line-131"></a> <span class='hs-keyword'>case</span> <span class='hs-varid'>y</span> <span class='hs-keyword'>of</span>
<a name="line-132"></a> <span class='hs-conid'>Left</span> <span class='hs-varid'>r</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-layout'>(</span><span class='hs-varid'>return</span> <span class='hs-varid'>r</span><span class='hs-layout'>)</span>
<a name="line-133"></a> <span class='hs-conid'>Right</span> <span class='hs-layout'>(</span><span class='hs-varid'>a'</span><span class='hs-layout'>,</span> <span class='hs-varid'>p'</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span>
<a name="line-134"></a> <span class='hs-keyword'>if</span> <span class='hs-varid'>equals</span> <span class='hs-varid'>a</span> <span class='hs-varid'>a'</span>
<a name="line-135"></a> <span class='hs-keyword'>then</span> <span class='hs-keyword'>do</span>
<a name="line-136"></a> <span class='hs-varid'>yield</span> <span class='hs-varid'>a'</span>
<a name="line-137"></a> <span class='hs-varid'>loop1</span> <span class='hs-varid'>a'</span> <span class='hs-varid'>p'</span>
<a name="line-138"></a> <span class='hs-keyword'>else</span> <span class='hs-varid'>return</span> <span class='hs-layout'>(</span><span class='hs-varid'>yield</span> <span class='hs-varid'>a'</span> <span class='hs-varop'>>></span> <span class='hs-varid'>p'</span><span class='hs-layout'>)</span>
<a name="line-139"></a> <span class='hs-varid'>loop1</span> <span class='hs-varid'>a2</span> <span class='hs-varid'>p2</span>
<a name="line-140"></a><span class='hs-comment'>{-# INLINABLE groupsBy' #-}</span>
<a name="line-141"></a>
<a name="line-142"></a><a name="groups"></a><span class='hs-comment'>{-| Like 'groupsBy', where the equality predicate is ('==')
<a name="line-143"></a>
<a name="line-144"></a>>>> import Lens.Family (view)
<a name="line-145"></a>>>> import Pipes (yield, each)
<a name="line-146"></a>>>> import Pipes.Prelude (toList)
<a name="line-147"></a>>>> (toList . intercalates (yield '|') . view groups) (each "12233345")
<a name="line-148"></a>"1|22|333|4|5"
<a name="line-149"></a>
<a name="line-150"></a> You can think of this as:
<a name="line-151"></a>
<a name="line-152"></a>> groups
<a name="line-153"></a>> :: (Monad m, Eq a) => Lens' (Producer a m x) (FreeT (Producer a m) m x)
<a name="line-154"></a>-}</span>
<a name="line-155"></a><span class='hs-definition'>groups</span> <span class='hs-keyglyph'>::</span> <span class='hs-layout'>(</span><span class='hs-conid'>Monad</span> <span class='hs-varid'>m</span><span class='hs-layout'>,</span> <span class='hs-conid'>Eq</span> <span class='hs-varid'>a'</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>Lens</span> <span class='hs-layout'>(</span><span class='hs-conid'>Producer</span> <span class='hs-varid'>a'</span> <span class='hs-varid'>m</span> <span class='hs-varid'>x</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-conid'>Producer</span> <span class='hs-varid'>a</span> <span class='hs-varid'>m</span> <span class='hs-varid'>x</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-conid'>FreeT</span> <span class='hs-layout'>(</span><span class='hs-conid'>Producer</span> <span class='hs-varid'>a'</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-varid'>m</span> <span class='hs-varid'>x</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-conid'>FreeT</span> <span class='hs-layout'>(</span><span class='hs-conid'>Producer</span> <span class='hs-varid'>a</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-varid'>m</span> <span class='hs-varid'>x</span><span class='hs-layout'>)</span>
<a name="line-156"></a><span class='hs-definition'>groups</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>groupsBy</span> <span class='hs-layout'>(</span><span class='hs-varop'>==</span><span class='hs-layout'>)</span>
<a name="line-157"></a><span class='hs-comment'>{-# INLINABLE groups #-}</span>
<a name="line-158"></a>
<a name="line-159"></a><a name="chunksOf"></a><span class='hs-comment'>{-| 'chunksOf' is an splits a 'Producer' into a 'FreeT' of 'Producer's of fixed
<a name="line-160"></a> length
<a name="line-161"></a>
<a name="line-162"></a>>>> import Lens.Family (view)
<a name="line-163"></a>>>> import Pipes (yield, each)
<a name="line-164"></a>>>> import Pipes.Prelude (toList)
<a name="line-165"></a>>>> (toList . intercalates (yield '|') . view (chunksOf 3)) (each "12233345")
<a name="line-166"></a>"122|333|45"
<a name="line-167"></a>
<a name="line-168"></a> You can think of this as:
<a name="line-169"></a>
<a name="line-170"></a>> chunksOf
<a name="line-171"></a>> :: Monad m => Int -> Lens' (Producer a m x) (FreeT (Producer a m) m x)
<a name="line-172"></a>-}</span>
<a name="line-173"></a><span class='hs-definition'>chunksOf</span>
<a name="line-174"></a> <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-conid'>Int</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Lens</span> <span class='hs-layout'>(</span><span class='hs-conid'>Producer</span> <span class='hs-varid'>a'</span> <span class='hs-varid'>m</span> <span class='hs-varid'>x</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-conid'>Producer</span> <span class='hs-varid'>a</span> <span class='hs-varid'>m</span> <span class='hs-varid'>x</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-conid'>FreeT</span> <span class='hs-layout'>(</span><span class='hs-conid'>Producer</span> <span class='hs-varid'>a'</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-varid'>m</span> <span class='hs-varid'>x</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-conid'>FreeT</span> <span class='hs-layout'>(</span><span class='hs-conid'>Producer</span> <span class='hs-varid'>a</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-varid'>m</span> <span class='hs-varid'>x</span><span class='hs-layout'>)</span>
<a name="line-175"></a><span class='hs-definition'>chunksOf</span> <span class='hs-varid'>n0</span> <span class='hs-varid'>k</span> <span class='hs-varid'>p0</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>fmap</span> <span class='hs-varid'>concats</span> <span class='hs-layout'>(</span><span class='hs-varid'>k</span> <span class='hs-layout'>(</span><span class='hs-sel'>_chunksOf</span> <span class='hs-varid'>p0</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-176"></a> <span class='hs-keyword'>where</span>
<a name="line-177"></a><span class='hs-comment'>-- _chunksOf :: Monad m => Producer a m x -> FreeT (Producer a m) m x</span>
<a name="line-178"></a> <span class='hs-sel'>_chunksOf</span> <span class='hs-varid'>p</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>FreeT</span> <span class='hs-varop'>$</span> <span class='hs-keyword'>do</span>
<a name="line-179"></a> <span class='hs-varid'>x</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>next</span> <span class='hs-varid'>p</span>
<a name="line-180"></a> <span class='hs-varid'>return</span> <span class='hs-varop'>$</span> <span class='hs-keyword'>case</span> <span class='hs-varid'>x</span> <span class='hs-keyword'>of</span>
<a name="line-181"></a> <span class='hs-conid'>Left</span> <span class='hs-varid'>r</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Pure</span> <span class='hs-varid'>r</span>
<a name="line-182"></a> <span class='hs-conid'>Right</span> <span class='hs-layout'>(</span><span class='hs-varid'>a</span><span class='hs-layout'>,</span> <span class='hs-varid'>p'</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Free</span> <span class='hs-varop'>$</span> <span class='hs-varid'>fmap</span> <span class='hs-sel'>_chunksOf</span> <span class='hs-layout'>(</span><span class='hs-layout'>(</span><span class='hs-varid'>yield</span> <span class='hs-varid'>a</span> <span class='hs-varop'>>></span> <span class='hs-varid'>p'</span><span class='hs-layout'>)</span><span class='hs-varop'>^.</span><span class='hs-varid'>splitAt</span> <span class='hs-varid'>n0</span><span class='hs-layout'>)</span>
<a name="line-183"></a><span class='hs-comment'>{-# INLINABLE chunksOf #-}</span>
<a name="line-184"></a>
<a name="line-185"></a><a name="concats"></a><span class='hs-comment'>-- | Join a 'FreeT'-delimited stream of 'Producer's into a single 'Producer'</span>
<a name="line-186"></a><span class='hs-definition'>concats</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-conid'>FreeT</span> <span class='hs-layout'>(</span><span class='hs-conid'>Producer</span> <span class='hs-varid'>a</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-varid'>m</span> <span class='hs-varid'>x</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Producer</span> <span class='hs-varid'>a</span> <span class='hs-varid'>m</span> <span class='hs-varid'>x</span>
<a name="line-187"></a><span class='hs-definition'>concats</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>go</span>
<a name="line-188"></a> <span class='hs-keyword'>where</span>
<a name="line-189"></a> <span class='hs-varid'>go</span> <span class='hs-varid'>f</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>do</span>
<a name="line-190"></a> <span class='hs-varid'>x</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>lift</span> <span class='hs-layout'>(</span><span class='hs-varid'>runFreeT</span> <span class='hs-varid'>f</span><span class='hs-layout'>)</span>
<a name="line-191"></a> <span class='hs-keyword'>case</span> <span class='hs-varid'>x</span> <span class='hs-keyword'>of</span>
<a name="line-192"></a> <span class='hs-conid'>Pure</span> <span class='hs-varid'>r</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-varid'>r</span>
<a name="line-193"></a> <span class='hs-conid'>Free</span> <span class='hs-varid'>p</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>do</span>
<a name="line-194"></a> <span class='hs-varid'>f'</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>p</span>
<a name="line-195"></a> <span class='hs-varid'>go</span> <span class='hs-varid'>f'</span>
<a name="line-196"></a><span class='hs-comment'>{-# INLINABLE concats #-}</span>
<a name="line-197"></a>
<a name="line-198"></a><a name="intercalates"></a><span class='hs-comment'>{-| Join a 'FreeT'-delimited stream of 'Producer's into a single 'Producer' by
<a name="line-199"></a> intercalating a 'Producer' in between them
<a name="line-200"></a>-}</span>
<a name="line-201"></a><span class='hs-definition'>intercalates</span>
<a name="line-202"></a> <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-conid'>Producer</span> <span class='hs-varid'>a</span> <span class='hs-varid'>m</span> <span class='hs-conid'>()</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>FreeT</span> <span class='hs-layout'>(</span><span class='hs-conid'>Producer</span> <span class='hs-varid'>a</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-varid'>m</span> <span class='hs-varid'>x</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Producer</span> <span class='hs-varid'>a</span> <span class='hs-varid'>m</span> <span class='hs-varid'>x</span>
<a name="line-203"></a><span class='hs-definition'>intercalates</span> <span class='hs-varid'>sep</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>go0</span>
<a name="line-204"></a> <span class='hs-keyword'>where</span>
<a name="line-205"></a> <span class='hs-varid'>go0</span> <span class='hs-varid'>f</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>do</span>
<a name="line-206"></a> <span class='hs-varid'>x</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>lift</span> <span class='hs-layout'>(</span><span class='hs-varid'>runFreeT</span> <span class='hs-varid'>f</span><span class='hs-layout'>)</span>
<a name="line-207"></a> <span class='hs-keyword'>case</span> <span class='hs-varid'>x</span> <span class='hs-keyword'>of</span>
<a name="line-208"></a> <span class='hs-conid'>Pure</span> <span class='hs-varid'>r</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-varid'>r</span>
<a name="line-209"></a> <span class='hs-conid'>Free</span> <span class='hs-varid'>p</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>do</span>
<a name="line-210"></a> <span class='hs-varid'>f'</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>p</span>
<a name="line-211"></a> <span class='hs-varid'>go1</span> <span class='hs-varid'>f'</span>
<a name="line-212"></a> <span class='hs-varid'>go1</span> <span class='hs-varid'>f</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>do</span>
<a name="line-213"></a> <span class='hs-varid'>x</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>lift</span> <span class='hs-layout'>(</span><span class='hs-varid'>runFreeT</span> <span class='hs-varid'>f</span><span class='hs-layout'>)</span>
<a name="line-214"></a> <span class='hs-keyword'>case</span> <span class='hs-varid'>x</span> <span class='hs-keyword'>of</span>
<a name="line-215"></a> <span class='hs-conid'>Pure</span> <span class='hs-varid'>r</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-varid'>r</span>
<a name="line-216"></a> <span class='hs-conid'>Free</span> <span class='hs-varid'>p</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>do</span>
<a name="line-217"></a> <span class='hs-varid'>sep</span>
<a name="line-218"></a> <span class='hs-varid'>f'</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>p</span>
<a name="line-219"></a> <span class='hs-varid'>go1</span> <span class='hs-varid'>f'</span>
<a name="line-220"></a><span class='hs-comment'>{-# INLINABLE intercalates #-}</span>
<a name="line-221"></a>
<a name="line-222"></a><a name="takes"></a><span class='hs-comment'>{-| @(takes n)@ only keeps the first @n@ functor layers of a 'FreeT'
<a name="line-223"></a>
<a name="line-224"></a>>>> import Lens.Family (view)
<a name="line-225"></a>>>> import Pipes (yield, each)
<a name="line-226"></a>>>> import Pipes.Prelude (toList)
<a name="line-227"></a>>>> (toList . intercalates (yield '|') . takes 3 . view groups) (each "12233345")
<a name="line-228"></a>"1|22|333"
<a name="line-229"></a>
<a name="line-230"></a> You can think of this as:
<a name="line-231"></a>
<a name="line-232"></a>> takes
<a name="line-233"></a>> :: (Functor f, Monad m)
<a name="line-234"></a>> => Int -> FreeT (Producer a m) m () -> FreeT (Producer a m) m ()
<a name="line-235"></a>-}</span>
<a name="line-236"></a><span class='hs-definition'>takes</span> <span class='hs-keyglyph'>::</span> <span class='hs-layout'>(</span><span class='hs-conid'>Functor</span> <span class='hs-varid'>f</span><span class='hs-layout'>,</span> <span class='hs-conid'>Monad</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>Int</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>FreeT</span> <span class='hs-varid'>f</span> <span class='hs-varid'>m</span> <span class='hs-conid'>()</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>FreeT</span> <span class='hs-varid'>f</span> <span class='hs-varid'>m</span> <span class='hs-conid'>()</span>
<a name="line-237"></a><span class='hs-definition'>takes</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>go</span>
<a name="line-238"></a> <span class='hs-keyword'>where</span>
<a name="line-239"></a> <span class='hs-varid'>go</span> <span class='hs-varid'>n</span> <span class='hs-varid'>f</span> <span class='hs-keyglyph'>=</span>
<a name="line-240"></a> <span class='hs-keyword'>if</span> <span class='hs-layout'>(</span><span class='hs-varid'>n</span> <span class='hs-varop'>></span> <span class='hs-num'>0</span><span class='hs-layout'>)</span>
<a name="line-241"></a> <span class='hs-keyword'>then</span> <span class='hs-conid'>FreeT</span> <span class='hs-varop'>$</span> <span class='hs-keyword'>do</span>
<a name="line-242"></a> <span class='hs-varid'>x</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>runFreeT</span> <span class='hs-varid'>f</span>
<a name="line-243"></a> <span class='hs-keyword'>case</span> <span class='hs-varid'>x</span> <span class='hs-keyword'>of</span>
<a name="line-244"></a> <span class='hs-conid'>Pure</span> <span class='hs-conid'>()</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-layout'>(</span><span class='hs-conid'>Pure</span> <span class='hs-conid'>()</span><span class='hs-layout'>)</span>
<a name="line-245"></a> <span class='hs-conid'>Free</span> <span class='hs-varid'>w</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-layout'>(</span><span class='hs-conid'>Free</span> <span class='hs-layout'>(</span><span class='hs-varid'>fmap</span> <span class='hs-layout'>(</span><span class='hs-varid'>go</span> <span class='hs-varop'>$!</span> <span class='hs-varid'>n</span> <span class='hs-comment'>-</span> <span class='hs-num'>1</span><span class='hs-layout'>)</span> <span class='hs-varid'>w</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-246"></a> <span class='hs-keyword'>else</span> <span class='hs-varid'>return</span> <span class='hs-conid'>()</span>
<a name="line-247"></a><span class='hs-comment'>{-# INLINABLE takes #-}</span>
<a name="line-248"></a>
<a name="line-249"></a><a name="takes'"></a><span class='hs-comment'>{-| @(takes' n)@ only keeps the first @n@ 'Producer's of a 'FreeT'
<a name="line-250"></a>
<a name="line-251"></a> 'takes'' differs from 'takes' by draining unused 'Producer's in order
<a name="line-252"></a> to preserve the return value. This makes it a suitable argument for 'maps'.
<a name="line-253"></a>-}</span>
<a name="line-254"></a><span class='hs-definition'>takes'</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-conid'>Int</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>FreeT</span> <span class='hs-layout'>(</span><span class='hs-conid'>Producer</span> <span class='hs-varid'>a</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-varid'>m</span> <span class='hs-varid'>x</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>FreeT</span> <span class='hs-layout'>(</span><span class='hs-conid'>Producer</span> <span class='hs-varid'>a</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-varid'>m</span> <span class='hs-varid'>x</span>
<a name="line-255"></a><span class='hs-definition'>takes'</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>go0</span>
<a name="line-256"></a> <span class='hs-keyword'>where</span>
<a name="line-257"></a> <span class='hs-varid'>go0</span> <span class='hs-varid'>n</span> <span class='hs-varid'>f</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>FreeT</span> <span class='hs-varop'>$</span>
<a name="line-258"></a> <span class='hs-keyword'>if</span> <span class='hs-layout'>(</span><span class='hs-varid'>n</span> <span class='hs-varop'>></span> <span class='hs-num'>0</span><span class='hs-layout'>)</span>
<a name="line-259"></a> <span class='hs-keyword'>then</span> <span class='hs-keyword'>do</span>
<a name="line-260"></a> <span class='hs-varid'>x</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>runFreeT</span> <span class='hs-varid'>f</span>
<a name="line-261"></a> <span class='hs-varid'>return</span> <span class='hs-varop'>$</span> <span class='hs-keyword'>case</span> <span class='hs-varid'>x</span> <span class='hs-keyword'>of</span>
<a name="line-262"></a> <span class='hs-conid'>Pure</span> <span class='hs-varid'>r</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Pure</span> <span class='hs-varid'>r</span>
<a name="line-263"></a> <span class='hs-conid'>Free</span> <span class='hs-varid'>p</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Free</span> <span class='hs-varop'>$</span> <span class='hs-varid'>fmap</span> <span class='hs-layout'>(</span><span class='hs-varid'>go0</span> <span class='hs-varop'>$!</span> <span class='hs-varid'>n</span> <span class='hs-comment'>-</span> <span class='hs-num'>1</span><span class='hs-layout'>)</span> <span class='hs-varid'>p</span>
<a name="line-264"></a> <span class='hs-keyword'>else</span> <span class='hs-varid'>go1</span> <span class='hs-varid'>f</span>
<a name="line-265"></a> <span class='hs-varid'>go1</span> <span class='hs-varid'>f</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>do</span>
<a name="line-266"></a> <span class='hs-varid'>x</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>runFreeT</span> <span class='hs-varid'>f</span>
<a name="line-267"></a> <span class='hs-keyword'>case</span> <span class='hs-varid'>x</span> <span class='hs-keyword'>of</span>
<a name="line-268"></a> <span class='hs-conid'>Pure</span> <span class='hs-varid'>r</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-layout'>(</span><span class='hs-conid'>Pure</span> <span class='hs-varid'>r</span><span class='hs-layout'>)</span>
<a name="line-269"></a> <span class='hs-conid'>Free</span> <span class='hs-varid'>p</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>do</span>
<a name="line-270"></a> <span class='hs-varid'>f'</span> <span class='hs-keyglyph'><-</span> <span class='hs-conid'>P</span><span class='hs-varop'>.</span><span class='hs-varid'>runEffect</span> <span class='hs-layout'>(</span><span class='hs-conid'>P</span><span class='hs-varop'>.</span><span class='hs-varid'>for</span> <span class='hs-varid'>p</span> <span class='hs-conid'>P</span><span class='hs-varop'>.</span><span class='hs-varid'>discard</span><span class='hs-layout'>)</span>
<a name="line-271"></a> <span class='hs-varid'>go1</span> <span class='hs-varid'>f'</span>
<a name="line-272"></a><span class='hs-comment'>{-# INLINABLE takes' #-}</span>
<a name="line-273"></a>
<a name="line-274"></a><a name="drops"></a><span class='hs-comment'>{-| @(drops n)@ peels off the first @n@ 'Producer' layers of a 'FreeT'
<a name="line-275"></a>
<a name="line-276"></a>>>> import Lens.Family (view)
<a name="line-277"></a>>>> import Pipes (yield, each)
<a name="line-278"></a>>>> import Pipes.Prelude (toList)
<a name="line-279"></a>>>> (toList . intercalates (yield '|') . drops 3 . view groups) (each "12233345")
<a name="line-280"></a>"4|5"
<a name="line-281"></a>
<a name="line-282"></a> __Use carefully__: the peeling off is not free. This runs the first @n@
<a name="line-283"></a> layers, just discarding everything they produce.
<a name="line-284"></a>-}</span>
<a name="line-285"></a><span class='hs-definition'>drops</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-conid'>Int</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>FreeT</span> <span class='hs-layout'>(</span><span class='hs-conid'>Producer</span> <span class='hs-varid'>a</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-varid'>m</span> <span class='hs-varid'>x</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>FreeT</span> <span class='hs-layout'>(</span><span class='hs-conid'>Producer</span> <span class='hs-varid'>a</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-varid'>m</span> <span class='hs-varid'>x</span>
<a name="line-286"></a><span class='hs-definition'>drops</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>go</span>
<a name="line-287"></a> <span class='hs-keyword'>where</span>
<a name="line-288"></a> <span class='hs-varid'>go</span> <span class='hs-varid'>n</span> <span class='hs-varid'>ft</span>
<a name="line-289"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>n</span> <span class='hs-varop'><=</span> <span class='hs-num'>0</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>ft</span>
<a name="line-290"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>otherwise</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>FreeT</span> <span class='hs-varop'>$</span> <span class='hs-keyword'>do</span>
<a name="line-291"></a> <span class='hs-varid'>ff</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>runFreeT</span> <span class='hs-varid'>ft</span>
<a name="line-292"></a> <span class='hs-keyword'>case</span> <span class='hs-varid'>ff</span> <span class='hs-keyword'>of</span>
<a name="line-293"></a> <span class='hs-conid'>Pure</span> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-varid'>ff</span>
<a name="line-294"></a> <span class='hs-conid'>Free</span> <span class='hs-varid'>f</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>do</span>
<a name="line-295"></a> <span class='hs-varid'>ft'</span> <span class='hs-keyglyph'><-</span> <span class='hs-conid'>P</span><span class='hs-varop'>.</span><span class='hs-varid'>runEffect</span> <span class='hs-varop'>$</span> <span class='hs-conid'>P</span><span class='hs-varop'>.</span><span class='hs-varid'>for</span> <span class='hs-varid'>f</span> <span class='hs-conid'>P</span><span class='hs-varop'>.</span><span class='hs-varid'>discard</span>
<a name="line-296"></a> <span class='hs-varid'>runFreeT</span> <span class='hs-varop'>$</span> <span class='hs-varid'>go</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> <span class='hs-varid'>ft'</span>
<a name="line-297"></a><span class='hs-comment'>{-# INLINABLE drops #-}</span>
<a name="line-298"></a>
<a name="line-299"></a><a name="maps"></a><span class='hs-comment'>{-| Transform each individual functor layer of a 'FreeT'
<a name="line-300"></a>
<a name="line-301"></a> You can think of this as:
<a name="line-302"></a>
<a name="line-303"></a>> maps
<a name="line-304"></a>> :: (forall r . Producer a m r -> Producer b m r)
<a name="line-305"></a>> -> FreeT (Producer a m) m x -> FreeT (Producer b m) m x
<a name="line-306"></a>
<a name="line-307"></a> This is just a synonym for 'F.transFreeT'
<a name="line-308"></a>-}</span>
<a name="line-309"></a><span class='hs-definition'>maps</span>
<a name="line-310"></a> <span class='hs-keyglyph'>::</span> <span class='hs-layout'>(</span><span class='hs-conid'>Monad</span> <span class='hs-varid'>m</span><span class='hs-layout'>,</span> <span class='hs-conid'>Functor</span> <span class='hs-varid'>g</span><span class='hs-layout'>)</span>
<a name="line-311"></a> <span class='hs-keyglyph'>=></span> <span class='hs-layout'>(</span><span class='hs-keyword'>forall</span> <span class='hs-varid'>r</span> <span class='hs-varop'>.</span> <span class='hs-varid'>f</span> <span class='hs-varid'>r</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>g</span> <span class='hs-varid'>r</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>FreeT</span> <span class='hs-varid'>f</span> <span class='hs-varid'>m</span> <span class='hs-varid'>x</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>FreeT</span> <span class='hs-varid'>g</span> <span class='hs-varid'>m</span> <span class='hs-varid'>x</span>
<a name="line-312"></a><span class='hs-definition'>maps</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>F</span><span class='hs-varop'>.</span><span class='hs-varid'>transFreeT</span>
<a name="line-313"></a><span class='hs-comment'>{-# INLINABLE maps #-}</span>
<a name="line-314"></a>
<a name="line-315"></a><a name="individually"></a><span class='hs-comment'>{-| Lens to transform each individual functor layer of a 'FreeT'
<a name="line-316"></a>
<a name="line-317"></a>> over individually = maps -- ... with a less general type
<a name="line-318"></a>-}</span>
<a name="line-319"></a><span class='hs-definition'>individually</span>
<a name="line-320"></a> <span class='hs-keyglyph'>::</span> <span class='hs-layout'>(</span><span class='hs-conid'>Monad</span> <span class='hs-varid'>m</span><span class='hs-layout'>,</span> <span class='hs-conid'>Functor</span> <span class='hs-varid'>g</span><span class='hs-layout'>)</span>
<a name="line-321"></a> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>Setter</span> <span class='hs-layout'>(</span><span class='hs-conid'>FreeT</span> <span class='hs-varid'>f</span> <span class='hs-varid'>m</span> <span class='hs-varid'>x</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-conid'>FreeT</span> <span class='hs-varid'>g</span> <span class='hs-varid'>m</span> <span class='hs-varid'>x</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-varid'>f</span> <span class='hs-layout'>(</span><span class='hs-conid'>FreeT</span> <span class='hs-varid'>f</span> <span class='hs-varid'>m</span> <span class='hs-varid'>x</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-varid'>g</span> <span class='hs-layout'>(</span><span class='hs-conid'>FreeT</span> <span class='hs-varid'>f</span> <span class='hs-varid'>m</span> <span class='hs-varid'>x</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-322"></a><span class='hs-definition'>individually</span> <span class='hs-varid'>nat</span> <span class='hs-varid'>f0</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Identity</span> <span class='hs-layout'>(</span><span class='hs-varid'>go</span> <span class='hs-varid'>f0</span><span class='hs-layout'>)</span>
<a name="line-323"></a> <span class='hs-keyword'>where</span>
<a name="line-324"></a> <span class='hs-varid'>nat'</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>runIdentity</span> <span class='hs-varop'>.</span> <span class='hs-varid'>nat</span>
<a name="line-325"></a> <span class='hs-varid'>go</span> <span class='hs-varid'>f</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>FreeT</span> <span class='hs-varop'>$</span> <span class='hs-keyword'>do</span>
<a name="line-326"></a> <span class='hs-varid'>x</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>runFreeT</span> <span class='hs-varid'>f</span>
<a name="line-327"></a> <span class='hs-varid'>return</span> <span class='hs-varop'>$</span> <span class='hs-keyword'>case</span> <span class='hs-varid'>x</span> <span class='hs-keyword'>of</span>
<a name="line-328"></a> <span class='hs-conid'>Pure</span> <span class='hs-varid'>r</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Pure</span> <span class='hs-varid'>r</span>
<a name="line-329"></a> <span class='hs-conid'>Free</span> <span class='hs-varid'>w</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Free</span> <span class='hs-layout'>(</span><span class='hs-varid'>fmap</span> <span class='hs-varid'>go</span> <span class='hs-layout'>(</span><span class='hs-varid'>nat'</span> <span class='hs-varid'>w</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-330"></a><span class='hs-comment'>{-# INLINABLE individually #-}</span>
<a name="line-331"></a>
<a name="line-332"></a><a name="folds"></a><span class='hs-comment'>{- $folds
<a name="line-333"></a> These folds are designed to be compatible with the @foldl@ library. See
<a name="line-334"></a> the 'Control.Foldl.purely' and 'Control.Foldl.impurely' functions from that
<a name="line-335"></a> library for more details.
<a name="line-336"></a>
<a name="line-337"></a> For example, to count the number of 'Producer' layers in a 'FreeT', you can
<a name="line-338"></a> write:
<a name="line-339"></a>
<a name="line-340"></a>> import Control.Applicative (pure)
<a name="line-341"></a>> import qualified Control.Foldl as L
<a name="line-342"></a>> import Pipes.Group
<a name="line-343"></a>> import qualified Pipes.Prelude as P
<a name="line-344"></a>>
<a name="line-345"></a>> count :: Monad m => FreeT (Producer a m) m () -> m Int
<a name="line-346"></a>> count = P.sum . L.purely folds (pure 1)
<a name="line-347"></a>-}</span>
<a name="line-348"></a><span class='hs-comment'>{-| Fold each 'Producer' of a 'FreeT'
<a name="line-349"></a>
<a name="line-350"></a>> purely folds
<a name="line-351"></a>> :: Monad m => Fold a b -> FreeT (Producer a m) m r -> Producer b m r
<a name="line-352"></a>-}</span>
<a name="line-353"></a><span class='hs-definition'>folds</span>
<a name="line-354"></a> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Monad</span> <span class='hs-varid'>m</span>
<a name="line-355"></a> <span class='hs-keyglyph'>=></span> <span class='hs-layout'>(</span><span class='hs-varid'>x</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>x</span><span class='hs-layout'>)</span>
<a name="line-356"></a> <span class='hs-comment'>-- ^ Step function</span>
<a name="line-357"></a> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>x</span>
<a name="line-358"></a> <span class='hs-comment'>-- ^ Initial accumulator</span>
<a name="line-359"></a> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-varid'>x</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>b</span><span class='hs-layout'>)</span>
<a name="line-360"></a> <span class='hs-comment'>-- ^ Extraction function</span>
<a name="line-361"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>FreeT</span> <span class='hs-layout'>(</span><span class='hs-conid'>Producer</span> <span class='hs-varid'>a</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-varid'>m</span> <span class='hs-varid'>r</span>
<a name="line-362"></a> <span class='hs-comment'>-- ^</span>
<a name="line-363"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Producer</span> <span class='hs-varid'>b</span> <span class='hs-varid'>m</span> <span class='hs-varid'>r</span>
<a name="line-364"></a><span class='hs-definition'>folds</span> <span class='hs-varid'>step</span> <span class='hs-varid'>begin</span> <span class='hs-varid'>done</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>go</span>
<a name="line-365"></a> <span class='hs-keyword'>where</span>
<a name="line-366"></a> <span class='hs-varid'>go</span> <span class='hs-varid'>f</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>do</span>
<a name="line-367"></a> <span class='hs-varid'>x</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>lift</span> <span class='hs-layout'>(</span><span class='hs-varid'>runFreeT</span> <span class='hs-varid'>f</span><span class='hs-layout'>)</span>
<a name="line-368"></a> <span class='hs-keyword'>case</span> <span class='hs-varid'>x</span> <span class='hs-keyword'>of</span>
<a name="line-369"></a> <span class='hs-conid'>Pure</span> <span class='hs-varid'>r</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-varid'>r</span>
<a name="line-370"></a> <span class='hs-conid'>Free</span> <span class='hs-varid'>p</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>do</span>
<a name="line-371"></a> <span class='hs-layout'>(</span><span class='hs-varid'>f'</span><span class='hs-layout'>,</span> <span class='hs-varid'>b</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>lift</span> <span class='hs-layout'>(</span><span class='hs-varid'>fold</span> <span class='hs-varid'>p</span> <span class='hs-varid'>begin</span><span class='hs-layout'>)</span>
<a name="line-372"></a> <span class='hs-varid'>yield</span> <span class='hs-varid'>b</span>
<a name="line-373"></a> <span class='hs-varid'>go</span> <span class='hs-varid'>f'</span>
<a name="line-374"></a>
<a name="line-375"></a> <span class='hs-varid'>fold</span> <span class='hs-varid'>p</span> <span class='hs-varid'>x</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>do</span>
<a name="line-376"></a> <span class='hs-varid'>y</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>next</span> <span class='hs-varid'>p</span>
<a name="line-377"></a> <span class='hs-keyword'>case</span> <span class='hs-varid'>y</span> <span class='hs-keyword'>of</span>
<a name="line-378"></a> <span class='hs-conid'>Left</span> <span class='hs-varid'>f</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-layout'>(</span><span class='hs-varid'>f</span><span class='hs-layout'>,</span> <span class='hs-varid'>done</span> <span class='hs-varid'>x</span><span class='hs-layout'>)</span>
<a name="line-379"></a> <span class='hs-conid'>Right</span> <span class='hs-layout'>(</span><span class='hs-varid'>a</span><span class='hs-layout'>,</span> <span class='hs-varid'>p'</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>fold</span> <span class='hs-varid'>p'</span> <span class='hs-varop'>$!</span> <span class='hs-varid'>step</span> <span class='hs-varid'>x</span> <span class='hs-varid'>a</span>
<a name="line-380"></a><span class='hs-comment'>{-# INLINABLE folds #-}</span>
<a name="line-381"></a>
<a name="line-382"></a><a name="foldsM"></a><span class='hs-comment'>{-| Fold each 'Producer' of a 'FreeT', monadically
<a name="line-383"></a>
<a name="line-384"></a>> impurely foldsM
<a name="line-385"></a>> :: Monad m => FoldM a b -> FreeT (Producer a m) m r -> Producer b m r
<a name="line-386"></a>-}</span>
<a name="line-387"></a><span class='hs-definition'>foldsM</span>
<a name="line-388"></a> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Monad</span> <span class='hs-varid'>m</span>
<a name="line-389"></a> <span class='hs-keyglyph'>=></span> <span class='hs-layout'>(</span><span class='hs-varid'>x</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>m</span> <span class='hs-varid'>x</span><span class='hs-layout'>)</span>
<a name="line-390"></a> <span class='hs-comment'>-- ^ Step function</span>
<a name="line-391"></a> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>m</span> <span class='hs-varid'>x</span>
<a name="line-392"></a> <span class='hs-comment'>-- ^ Initial accumulator</span>
<a name="line-393"></a> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-varid'>x</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>m</span> <span class='hs-varid'>b</span><span class='hs-layout'>)</span>
<a name="line-394"></a> <span class='hs-comment'>-- ^ Extraction function</span>
<a name="line-395"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>FreeT</span> <span class='hs-layout'>(</span><span class='hs-conid'>Producer</span> <span class='hs-varid'>a</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-varid'>m</span> <span class='hs-varid'>r</span>
<a name="line-396"></a> <span class='hs-comment'>-- ^</span>
<a name="line-397"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Producer</span> <span class='hs-varid'>b</span> <span class='hs-varid'>m</span> <span class='hs-varid'>r</span>
<a name="line-398"></a><span class='hs-definition'>foldsM</span> <span class='hs-varid'>step</span> <span class='hs-varid'>begin</span> <span class='hs-varid'>done</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>go</span>
<a name="line-399"></a> <span class='hs-keyword'>where</span>
<a name="line-400"></a> <span class='hs-varid'>go</span> <span class='hs-varid'>f</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>do</span>
<a name="line-401"></a> <span class='hs-varid'>y</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>lift</span> <span class='hs-layout'>(</span><span class='hs-varid'>runFreeT</span> <span class='hs-varid'>f</span><span class='hs-layout'>)</span>
<a name="line-402"></a> <span class='hs-keyword'>case</span> <span class='hs-varid'>y</span> <span class='hs-keyword'>of</span>
<a name="line-403"></a> <span class='hs-conid'>Pure</span> <span class='hs-varid'>r</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-varid'>r</span>
<a name="line-404"></a> <span class='hs-conid'>Free</span> <span class='hs-varid'>p</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>do</span>
<a name="line-405"></a> <span class='hs-layout'>(</span><span class='hs-varid'>f'</span><span class='hs-layout'>,</span> <span class='hs-varid'>b</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>lift</span> <span class='hs-varop'>$</span> <span class='hs-keyword'>do</span>
<a name="line-406"></a> <span class='hs-varid'>x</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>begin</span>
<a name="line-407"></a> <span class='hs-varid'>foldM</span> <span class='hs-varid'>p</span> <span class='hs-varid'>x</span>
<a name="line-408"></a> <span class='hs-varid'>yield</span> <span class='hs-varid'>b</span>
<a name="line-409"></a> <span class='hs-varid'>go</span> <span class='hs-varid'>f'</span>
<a name="line-410"></a>
<a name="line-411"></a> <span class='hs-varid'>foldM</span> <span class='hs-varid'>p</span> <span class='hs-varid'>x</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>do</span>
<a name="line-412"></a> <span class='hs-varid'>y</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>next</span> <span class='hs-varid'>p</span>
<a name="line-413"></a> <span class='hs-keyword'>case</span> <span class='hs-varid'>y</span> <span class='hs-keyword'>of</span>
<a name="line-414"></a> <span class='hs-conid'>Left</span> <span class='hs-varid'>f</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>do</span>
<a name="line-415"></a> <span class='hs-varid'>b</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>done</span> <span class='hs-varid'>x</span>
<a name="line-416"></a> <span class='hs-varid'>return</span> <span class='hs-layout'>(</span><span class='hs-varid'>f</span><span class='hs-layout'>,</span> <span class='hs-varid'>b</span><span class='hs-layout'>)</span>
<a name="line-417"></a> <span class='hs-conid'>Right</span> <span class='hs-layout'>(</span><span class='hs-varid'>a</span><span class='hs-layout'>,</span> <span class='hs-varid'>p'</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>do</span>
<a name="line-418"></a> <span class='hs-varid'>x'</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>step</span> <span class='hs-varid'>x</span> <span class='hs-varid'>a</span>
<a name="line-419"></a> <span class='hs-varid'>foldM</span> <span class='hs-varid'>p'</span> <span class='hs-varop'>$!</span> <span class='hs-varid'>x'</span>
<a name="line-420"></a><span class='hs-comment'>{-# INLINABLE foldsM #-}</span>
<a name="line-421"></a><span class='hs-comment'>{- $reexports
<a name="line-422"></a> "Control.Monad.Trans.Class" re-exports 'lift'.
<a name="line-423"></a>
<a name="line-424"></a> "Control.Monad.Trans.Free" re-exports 'FreeF' and 'FreeT'
<a name="line-425"></a>
<a name="line-426"></a> "Pipes" re-exports 'Producer', 'yield', and 'next'.
<a name="line-427"></a>-}</span>
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