compare between half byte matching and full byte

gistfile1.txt

# Untitled notebook

```elixir
Mix.install([:benchee])
```

<!-- livebook:{"output":true} -->

```
:ok
```

## Section

```elixir
defmodule ParseInt do
  def parse_new(<<3::4, x0::4, 3::4, x1::4, 3::4, x2::4, 3::4, x3::4>>)
      when x0 < 10 and x1 < 10 and x2 < 10 and x3 < 10 do
    x3 + x2 * 10 + x1 * 100 + x0 * 1000
  end

  def nimble(<<x0, x1, x2, x3>>)
      when x0 >= 48 and x0 <= 57 and (x1 >= 48 and x1 <= 57) and
             (x2 >= 48 and x2 <= 57) and (x3 >= 48 and x3 <= 57) do
    (x3 - 48) * 1 + (x2 - 48) * 10 + (x1 - 48) * 100 + (x0 - 48) * 1000
  end
end

{ParseInt.parse_new("1123"), ParseInt.nimble("1123")}
```

<!-- livebook:{"output":true} -->

```
{1123, 1123}
```

```elixir
list = Enum.map(1000..9999, &to_string(&1))

Benchee.run(
  %{
    "original" => fn -> Enum.map(list, &ParseInt.nimble(&1)) end,
    "half byte" => fn -> Enum.map(list, &ParseInt.parse_new(&1)) end
  },
  time: 10,
  memory_time: 2
)
```

<!-- livebook:{"output":true} -->

```
Operating System: Linux
CPU Information: Intel(R) Core(TM) i5-7200U CPU @ 2.50GHz
Number of Available Cores: 4
Available memory: 7.41 GB
Elixir 1.15.2
Erlang 26.0.2

Benchmark suite executing with the following configuration:
warmup: 2 s
time: 10 s
memory time: 2 s
reduction time: 0 ns
parallel: 1
inputs: none specified
Estimated total run time: 28 s

Benchmarking half byte ...
Benchmarking original ...

Name                ips        average  deviation         median         99th %
half byte        3.04 K      328.56 μs    ±31.44%      277.56 μs      643.98 μs
original         2.93 K      341.79 μs    ±34.93%      288.44 μs      672.01 μs

Comparison: 
half byte        3.04 K
original         2.93 K - 1.04x slower +13.23 μs

Memory usage statistics:

Name         Memory usage
half byte       493.70 KB
original        493.70 KB - 1.00x memory usage +0 KB

**All measurements for memory usage were the same**
```

<!-- livebook:{"output":true} -->

```
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    available_memory: "7.41 GB"
  },
  configuration: %Benchee.Configuration{
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    time: 10000000000.0,
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    memory_time: 2000000000.0,
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    pre_check: false,
    formatters: [Benchee.Formatters.Console],
    percentiles: ~c"2c",
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    before_scenario: nil,
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    title: nil,
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    }
  ]
}
```