make nextPermutation faster

haskell · Jul 20, 2024 · b39874a · b39874a
1 parent 5d4226e
commit b39874a
Showing 1 changed file with 1 addition and 2 deletions.
diff --git a/vector/src/Data/Vector/Generic/Mutable.hs b/vector/src/Data/Vector/Generic/Mutable.hs
@@ -1243,8 +1243,7 @@ nextPermutation v
               | i == dim = return (k,l)
               | otherwise  = do
                   cur <- unsafeRead v i
-                  -- TODO: make tuple unboxed
-                  let (kval',k') = if prev < cur then (prev,i-1) else (kval,k)
+                  let (!kval',!k') = if prev < cur then (prev,i-1) else (kval,k)
                       l' = if kval' < cur then i else l
                   loop kval' k' l' cur (i+1)
           dim = length v