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27 lines
577 B
Idris
27 lines
577 B
Idris
import Data.List.Lazy
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import Debug.Trace
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%default total
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xs : LazyList Nat
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xs = iterateN 5 (traceValBy (("xs: " ++) . show) . S) Z
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ys : Maybe (List Nat)
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ys = for xs $ \n => if n >= 3 then Nothing else Just (10 * n)
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xs' : LazyList Nat
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xs' = iterateN 5 (traceValBy (("xs': " ++) . show) . S) Z
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for' : Monad f => LazyList a -> (a -> f b) -> f $ List b
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for' [] _ = pure []
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for' (x::xs) g = pure $ !(g x) :: !(for' xs g)
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ys' : Maybe (List Nat)
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ys' = for' xs' $ \n => if n >= 3 then Nothing else Just (10 * n)
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main : IO ()
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main = do
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putStrLn $ show ys
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putStrLn $ show ys'
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