Just trying out Haskell Stack
Includes the following:
- Different Fibonacci implementations
- Implementing read from stdin and calling a function
- Tests via HSpec
- Travis integration
- Benchmarking using criterion
$ stack exec fib-hs-exe
$ stack test
$ stack bench
-
Why is
fibLinear, which is linear and tail-recursive, slower thanfibClassic??Fib 30 takes 475.1 ns for
fibLinearvs 78.46 ns forfibClassic -
Why is
fibLinearBang, which is linear and tail-recursive, slower thanfibClassic??Fib 30 takes 279.5 ns for
fibLinearBangvs 78.46 ns forfibClassic
Let-floating, which is enabled by default because full-laziness is on by default in GHC,
causes the fib' local variable in fibClassic to get pulled out into something like a top-level constant.
Disabling let-floating by using the -fno-full-laziness flag turns the tables.
This was surprising (and a questionable default) to me because it could potentially have a disastrous effect on run-time memory usage (running fib to 100 million would result in holding a huge list in memory forever).
With default GHC options
fib-hs-0.1.0.0: benchmarks
Running 1 benchmarks...
Benchmark fib-hs-bench: RUNNING...
benchmarking fibNaive/10
time 915.0 ns (903.4 ns .. 927.9 ns)
0.998 R² (0.997 R² .. 0.999 R²)
mean 931.9 ns (918.1 ns .. 947.8 ns)
std dev 48.95 ns (40.02 ns .. 61.29 ns)
variance introduced by outliers: 69% (severely inflated)
benchmarking fibNaive/20
time 114.3 μs (112.0 μs .. 116.1 μs)
0.997 R² (0.996 R² .. 0.998 R²)
mean 112.5 μs (110.7 μs .. 114.2 μs)
std dev 5.882 μs (4.796 μs .. 7.396 μs)
variance introduced by outliers: 54% (severely inflated)
benchmarking fibNaive/30
time 14.19 ms (13.88 ms .. 14.55 ms)
0.997 R² (0.995 R² .. 0.999 R²)
mean 14.23 ms (14.01 ms .. 14.44 ms)
std dev 554.4 μs (432.9 μs .. 751.8 μs)
variance introduced by outliers: 15% (moderately inflated)
benchmarking fibLinear/10
time 124.1 ns (121.9 ns .. 126.4 ns)
0.998 R² (0.996 R² .. 0.998 R²)
mean 124.0 ns (121.8 ns .. 126.3 ns)
std dev 7.517 ns (6.068 ns .. 9.305 ns)
variance introduced by outliers: 78% (severely inflated)
benchmarking fibLinear/20
time 281.0 ns (276.5 ns .. 285.7 ns)
0.998 R² (0.997 R² .. 0.998 R²)
mean 282.6 ns (277.6 ns .. 288.0 ns)
std dev 16.78 ns (13.39 ns .. 21.98 ns)
variance introduced by outliers: 76% (severely inflated)
benchmarking fibLinear/30
time 466.4 ns (457.7 ns .. 475.3 ns)
0.997 R² (0.996 R² .. 0.998 R²)
mean 475.1 ns (465.9 ns .. 484.2 ns)
std dev 30.95 ns (25.34 ns .. 39.17 ns)
variance introduced by outliers: 78% (severely inflated)
benchmarking fibLinearBang/10
time 86.25 ns (84.90 ns .. 87.41 ns)
0.998 R² (0.997 R² .. 0.999 R²)
mean 85.64 ns (84.29 ns .. 86.91 ns)
std dev 4.444 ns (3.521 ns .. 5.833 ns)
variance introduced by outliers: 72% (severely inflated)
benchmarking fibLinearBang/20
time 187.9 ns (185.4 ns .. 190.8 ns)
0.997 R² (0.996 R² .. 0.998 R²)
mean 189.1 ns (185.4 ns .. 193.3 ns)
std dev 13.18 ns (10.75 ns .. 15.99 ns)
variance introduced by outliers: 82% (severely inflated)
benchmarking fibLinearBang/30
time 280.7 ns (276.7 ns .. 284.7 ns)
0.998 R² (0.997 R² .. 0.999 R²)
mean 279.5 ns (275.0 ns .. 284.4 ns)
std dev 15.69 ns (12.60 ns .. 19.62 ns)
variance introduced by outliers: 74% (severely inflated)
benchmarking fibClassic/10
time 29.74 ns (29.25 ns .. 30.37 ns)
0.997 R² (0.996 R² .. 0.998 R²)
mean 29.93 ns (29.43 ns .. 30.54 ns)
std dev 1.877 ns (1.578 ns .. 2.376 ns)
variance introduced by outliers: 81% (severely inflated)
benchmarking fibClassic/20
time 61.50 ns (60.39 ns .. 62.53 ns)
0.997 R² (0.996 R² .. 0.999 R²)
mean 61.74 ns (60.71 ns .. 62.84 ns)
std dev 3.594 ns (2.995 ns .. 4.470 ns)
variance introduced by outliers: 77% (severely inflated)
benchmarking fibClassic/30
time 78.00 ns (76.82 ns .. 79.06 ns)
0.998 R² (0.997 R² .. 0.999 R²)
mean 78.46 ns (77.16 ns .. 79.95 ns)
std dev 4.861 ns (3.899 ns .. 6.115 ns)
variance introduced by outliers: 79% (severely inflated)
Benchmark fib-hs-bench: FINISH
With -fno-full-laziness GHC option, which disables let-floating.
For more flags, see this list.
fib-hs-0.1.0.0: benchmarks
Running 1 benchmarks...
Benchmark fib-hs-bench: RUNNING...
benchmarking fibNaive/10
time 1.011 μs (991.5 ns .. 1.030 μs)
0.997 R² (0.996 R² .. 0.998 R²)
mean 1.006 μs (988.4 ns .. 1.026 μs)
std dev 66.08 ns (52.75 ns .. 84.40 ns)
variance introduced by outliers: 78% (severely inflated)
benchmarking fibNaive/20
time 121.4 μs (119.5 μs .. 123.6 μs)
0.996 R² (0.994 R² .. 0.998 R²)
mean 124.2 μs (121.9 μs .. 126.8 μs)
std dev 8.340 μs (6.625 μs .. 11.12 μs)
variance introduced by outliers: 66% (severely inflated)
benchmarking fibNaive/30
time 15.09 ms (14.56 ms .. 15.54 ms)
0.995 R² (0.991 R² .. 0.998 R²)
mean 15.58 ms (15.31 ms .. 15.85 ms)
std dev 712.8 μs (559.1 μs .. 917.2 μs)
variance introduced by outliers: 16% (moderately inflated)
benchmarking fibLinear/10
time 110.6 ns (108.8 ns .. 112.3 ns)
0.997 R² (0.996 R² .. 0.998 R²)
mean 110.2 ns (108.2 ns .. 112.3 ns)
std dev 6.664 ns (5.516 ns .. 8.040 ns)
variance introduced by outliers: 78% (severely inflated)
benchmarking fibLinear/20
time 260.8 ns (257.4 ns .. 263.7 ns)
0.998 R² (0.998 R² .. 0.999 R²)
mean 254.9 ns (251.4 ns .. 258.2 ns)
std dev 11.97 ns (10.70 ns .. 13.56 ns)
variance introduced by outliers: 66% (severely inflated)
benchmarking fibLinear/30
time 428.5 ns (425.6 ns .. 431.7 ns)
0.998 R² (0.997 R² .. 0.999 R²)
mean 431.4 ns (424.4 ns .. 439.1 ns)
std dev 24.65 ns (19.92 ns .. 31.54 ns)
variance introduced by outliers: 74% (severely inflated)
benchmarking fibLinearBang/10
time 82.07 ns (80.22 ns .. 83.94 ns)
0.997 R² (0.996 R² .. 0.998 R²)
mean 80.77 ns (79.33 ns .. 82.01 ns)
std dev 4.414 ns (3.734 ns .. 5.267 ns)
variance introduced by outliers: 75% (severely inflated)
benchmarking fibLinearBang/20
time 180.3 ns (177.5 ns .. 182.9 ns)
0.998 R² (0.997 R² .. 0.999 R²)
mean 177.8 ns (174.5 ns .. 180.7 ns)
std dev 9.882 ns (8.357 ns .. 12.08 ns)
variance introduced by outliers: 74% (severely inflated)
benchmarking fibLinearBang/30
time 256.8 ns (250.9 ns .. 263.8 ns)
0.996 R² (0.995 R² .. 0.998 R²)
mean 259.8 ns (255.7 ns .. 263.2 ns)
std dev 12.95 ns (10.76 ns .. 15.42 ns)
variance introduced by outliers: 69% (severely inflated)
benchmarking fibClassic/10
time 238.1 ns (234.5 ns .. 242.5 ns)
0.997 R² (0.995 R² .. 0.998 R²)
mean 243.5 ns (239.4 ns .. 248.6 ns)
std dev 15.32 ns (12.51 ns .. 18.82 ns)
variance introduced by outliers: 78% (severely inflated)
benchmarking fibClassic/20
time 474.3 ns (469.0 ns .. 479.8 ns)
0.999 R² (0.998 R² .. 0.999 R²)
mean 474.0 ns (470.5 ns .. 480.4 ns)
std dev 15.57 ns (9.727 ns .. 23.87 ns)
variance introduced by outliers: 47% (moderately inflated)
benchmarking fibClassic/30
time 731.2 ns (720.0 ns .. 742.9 ns)
0.998 R² (0.997 R² .. 0.999 R²)
mean 738.4 ns (727.3 ns .. 749.5 ns)
std dev 40.12 ns (33.71 ns .. 52.35 ns)
variance introduced by outliers: 71% (severely inflated)
Benchmark fib-hs-bench: FINISH