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eulerfx/HListFoldish.fs

Last active August 29, 2015 14:14
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F# HList unsafe fold
Raw
HListFoldish.fs
// for http://www.fssnip.net/d2
type Fold<'b> = Fold of f:('b -> obj -> 'b) * z:'b
with
static member inline ($) (Fold(_,z), HNil) = z
static member inline ($) (Fold(f,z), HCons(a,xs)) = f (Fold(f,z) |*| xs) a
// use
let inline fold (hl:#HList) (f:Fold<'b>) : 'b = f $ hl
let inline foldLength hl = fold hl (Fold((fun l _ -> l + 1), 0))
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