All
  countdown
    1000
      shallow
        reference:                OK (0.23s)
          7.2 μs ± 354 ns,  16 KB allocated,  16 B  copied
        effectful (pure-static):  OK (0.15s)
          9.6 μs ± 655 ns,  17 KB allocated,  21 B  copied
        effectful (pure-dynamic): OK (0.13s)
           32 μs ± 2.8 μs, 213 KB allocated, 336 B  copied
        effectful (MVar-static):  OK (0.15s)
           37 μs ± 2.7 μs, 118 KB allocated, 157 B  copied
        effectful (MVar-dynamic): OK (0.21s)
           52 μs ± 2.7 μs, 291 KB allocated, 470 B  copied
        eff:                      OK (0.12s)
           62 μs ± 5.4 μs, 289 KB allocated, 344 B  copied
        mtl:                      OK (0.18s)
           87 μs ± 5.3 μs, 485 KB allocated, 580 B  copied
        fused-effects:            OK (0.17s)
          167 μs ±  11 μs, 897 KB allocated, 1.0 KB copied
      deep
        effectful (pure-static):  OK (0.19s)
           12 μs ± 721 ns,  25 KB allocated,  51 B  copied
        effectful (pure-dynamic): OK (0.14s)
           35 μs ± 2.8 μs, 221 KB allocated, 569 B  copied
        effectful (MVar-static):  OK (0.17s)
           40 μs ± 3.4 μs, 126 KB allocated, 178 B  copied
        effectful (MVar-dynamic): OK (0.22s)
           56 μs ± 2.6 μs, 300 KB allocated, 775 B  copied
        eff:                      OK (0.12s)
           64 μs ± 5.3 μs, 296 KB allocated, 1.1 KB copied
        mtl:                      OK (0.14s)
          558 μs ±  43 μs, 3.5 MB allocated, 5.2 KB copied
        fused-effects:            OK (0.17s)
          1.4 ms ±  92 μs, 6.2 MB allocated, 9.2 KB copied
    10000
      shallow
        reference:                OK (0.16s)
           81 μs ± 5.4 μs, 156 KB allocated, 148 B  copied
        effectful (pure-static):  OK (0.19s)
           99 μs ± 5.3 μs, 157 KB allocated, 181 B  copied
        effectful (pure-dynamic): OK (0.16s)
          327 μs ±  22 μs, 2.1 MB allocated,  11 KB copied
        effectful (MVar-static):  OK (0.20s)
          374 μs ±  21 μs, 1.1 MB allocated, 1.7 KB copied
        effectful (MVar-dynamic): OK (0.14s)
          527 μs ±  45 μs, 2.8 MB allocated, 9.1 KB copied
        eff:                      OK (0.14s)
          556 μs ±  45 μs, 2.8 MB allocated, 3.0 KB copied
        mtl:                      OK (0.10s)
          900 μs ±  89 μs, 4.7 MB allocated, 5.1 KB copied
        fused-effects:            OK (0.22s)
          1.7 ms ±  87 μs, 8.8 MB allocated, 8.7 KB copied
      deep
        effectful (pure-static):  OK (0.21s)
           99 μs ± 5.5 μs, 165 KB allocated, 353 B  copied
        effectful (pure-dynamic): OK (0.17s)
          331 μs ±  23 μs, 2.1 MB allocated,  13 KB copied
        effectful (MVar-static):  OK (0.20s)
          388 μs ±  24 μs, 1.2 MB allocated, 2.9 KB copied
        effectful (MVar-dynamic): OK (0.14s)
          544 μs ±  52 μs, 2.8 MB allocated,  11 KB copied
        eff:                      OK (0.14s)
          551 μs ±  46 μs, 2.8 MB allocated, 8.4 KB copied
        mtl:                      OK (0.17s)
          5.8 ms ± 551 μs,  35 MB allocated,  47 KB copied
        fused-effects:            OK (0.10s)
           15 ms ± 1.4 ms,  62 MB allocated,  85 KB copied
  filesize
    100
      shallow
        reference:                OK (0.13s)
          120 μs ±  11 μs, 509 KB allocated,  32 KB copied
        effectful:                OK (0.12s)
          124 μs ±  11 μs, 552 KB allocated,  25 KB copied
        mtl:                      OK (0.15s)
          144 μs ±  11 μs, 615 KB allocated,  23 KB copied
        eff:                      OK (0.17s)
          161 μs ±  14 μs, 745 KB allocated,  27 KB copied
      deep
        effectful:                OK (0.25s)
          122 μs ± 5.5 μs, 560 KB allocated,  19 KB copied
        eff:                      OK (0.15s)
          162 μs ±  13 μs, 752 KB allocated,  28 KB copied
        mtl:                      OK (0.15s)
          293 μs ±  24 μs, 1.2 MB allocated,  34 KB copied
    1000
      shallow
        reference:                OK (0.11s)
          2.0 ms ± 171 μs, 5.0 MB allocated, 1.9 MB copied
        effectful:                OK (0.13s)
          2.2 ms ± 195 μs, 5.3 MB allocated, 2.1 MB copied
        mtl:                      OK (0.15s)
          2.4 ms ± 193 μs, 6.0 MB allocated, 2.2 MB copied
        eff:                      OK (0.16s)
          2.6 ms ± 178 μs, 7.3 MB allocated, 2.3 MB copied
      deep
        effectful:                OK (0.12s)
          2.1 ms ± 174 μs, 5.3 MB allocated, 2.1 MB copied
        eff:                      OK (0.16s)
          2.6 ms ± 186 μs, 7.3 MB allocated, 2.3 MB copied
        mtl:                      OK (0.23s)
          3.9 ms ± 183 μs,  12 MB allocated, 2.2 MB copied

All 44 tests passed (7.42s)