shithub: MicroHs

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Make length tail recursive.

--- a/lib/Data/List.hs

+++ b/lib/Data/List.hs

@@ -100,8 +100,14 @@

       _ : xs -> drop (n - 1) xs

 length :: forall a . [a] -> P.Int

-length [] = 0

-length (_:xs) = 1 + length xs

+length =

+  -- Make it tail recursive and strict

+  let

+    rec r [] = r

+    rec r (_:xs) =

+          let r' = r + 1

+          in  r' `primSeq` rec r' xs

+  in rec 0

 zip :: forall a b . [a] -> [b] -> [(a, b)]

 zip = zipWith (\ x y -> (x, y))

-- 

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