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(.module:
[lux #*]
[//
[monoid (#+ Monoid)]])
(signature: #export (Fold F)
{#.doc "Iterate over a structure's values to build a summary value."}
(: (All [a b]
(-> (-> b a a) a (F b) a))
fold))
(def: #export (with-monoid monoid fold value)
(All [F a]
(-> (Monoid a) (Fold F) (F a) a))
(let [(^open "monoid;.") monoid]
(fold monoid;compose
monoid;identity
value)))
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