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{-# RULES
"fold/build" forall k z (g :: forall b. (a -> b -> b) -> b -> b).
foldr k z (build g) =
g k z
"foldr/augment" forall k z xs (g :: forall b. (a -> b -> b) -> b -> b).
foldr k z (augment g xs) =
g k (foldr k z xs)
"foldr/id" foldr (:) [] = \x -> x
"foldr/app" [1] forall ys. foldr (:) ys = \xs -> xs ++ ys
-- Only activate this from phase 1, because that's
-- when we disable the rule that expands (++) into foldr
-- The foldr/cons rule looks nice, but it can give disastrously
-- bloated code when commpiling
-- array (a,b) [(1,2), (2,2), (3,2), ...very long list... ]
-- i.e. when there are very very long literal lists
-- So I've disabled it for now. We could have special cases
-- for short lists, I suppose.
-- "foldr/cons" forall k z x xs. foldr k z (x:xs) = k x (foldr k z xs)
"foldr/single" forall k z x. foldr k z [x] = k x z
"foldr/nil" forall k z. foldr k z [] = z
"augment/build" forall
(g :: forall b. (a -> b -> b) -> b -> b)
(h :: forall b. (a -> b -> b) -> b -> b).
augment g (build h) =
build (\c n -> g c (h c n))
"augment/nil" forall (g :: forall b. (a -> b -> b) -> b -> b).
augment g [] =
build g
#-}
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