if bench

bench.hs

-- Which is faster?
-- Only difference is order of branches in 'if'.

sourceOfVector :: (Monad m, Generic.Vector v a) => v a -> Source m a
sourceOfVector !as0
 = Source 
 { init = return 0
 , pull = \ix -> if ix >= Generic.length as0
                 then return (Nothing, ix)
                 else return (Just $ Generic.unsafeIndex as0 ix, ix + 1)
 , done = \_  -> return ()
 }

{-# INLINE sourceOfVectorFlip #-}
sourceOfVectorFlip :: (Monad m, Generic.Vector v a) => v a -> Source m a
sourceOfVectorFlip !as0
 = Source 
 { init = return 0
 , pull = \ix -> if ix < Generic.length as0
                 then return (Just $ Generic.unsafeIndex as0 ix, ix + 1)
                 else return (Nothing, ix)
 , done = \_  -> return ()
 }


---------------------
{-
benchmarking sourceOfVector with ~80MB data
time                 15.26 ms   (15.11 ms .. 15.40 ms)
                     1.000 R²   (0.999 R² .. 1.000 R²)
mean                 15.31 ms   (15.18 ms .. 15.81 ms)
std dev              573.3 μs   (123.6 μs .. 1.164 ms)
variance introduced by outliers: 11% (moderately inflated)

benchmarking sourceOfVector with ~80MB data
time                 19.63 ms   (19.22 ms .. 20.13 ms)
                     0.998 R²   (0.996 R² .. 0.999 R²)
mean                 20.60 ms   (20.32 ms .. 20.80 ms)
std dev              569.2 μs   (443.3 μs .. 648.4 μs)

-}