As others have already menti9oned, running 'bc' isn't actually that expensive. Comparing it to Bitcoin is ridiculous. Let's investigate the actual cost of that sum:

    $ cat foo.sh 
    #!/bin/bash
    a="1.5"
    b="0.5"
    sum="$(echo "${a} + ${b}" | bc)"
    echo "The sum of ${a} and ${b} is ${sum}"

    $ /usr/bin/strace -q -D -w -c ./foo.sh 
    The sum of 1.5 and 0.5 is 2.0
    % time     seconds  usecs/call     calls    errors syscall
    ------ ----------- ----------- --------- --------- ----------------
     55.53    0.001225         123        10           read
      9.75    0.000215         215         1           execve
      5.53    0.000122           7        18           mmap
      4.03    0.000089           8        11         3 open
      3.04    0.000067           7        10           mprotect
      2.99    0.000066           5        13           rt_sigprocmask
      2.54    0.000056          56         1           clone
      2.45    0.000054           5        10           close
      2.40    0.000053           5        11           rt_sigaction
      1.81    0.000040           5         8           fstat
      1.41    0.000031           8         4           lseek
      1.22    0.000027           5         5         3 stat
      0.91    0.000020          20         1           write

That was 56us to clone(2) the process and 215us to execve(2) 'bc'. All together just 12.74% of the time spent running syscalls, and an even smaller portion of the total time to launch and execute this simple example. Most of the time is sent launching bash itself at the beginning. Using a language such as python or launching a custom binary will have similar costs to to launch the program. If we're talking about a single persistent process (e.g. an interactive shell), then we're still talking about paying just 0.25ms of CPU time to perform a useful calculation. Compared to intentionally wasting time by design maximizing hash prefix guesses to "mine" Bitcoin "ain't the same fuckin' ballpark, it ain't the same league, it ain't even the same fuckin' sport"[1].

However, the actual cost to launch an external program like 'bc' isn't particularly important. It could be multiple orders of magnitude slower and it would still be acceptable because we're talking ab9ut a cost that only needs to be paid a few times. Yes, compared to "full" programming languages like python, running an external program to perform a simple calculation might seem like a wasteful, half-assed solution. As Gary Bernhardt explained[2], "Half-assed is OK when you only need half of an ass."

I don't care about the cost of running 'bc' to do simple floating point calculations because I usually don't need to do floating point calculations (which are a lot harder to use safely[3] compared to simple integer math) for the type of task I would implement in a shell script. If the task required more than a few calculations (or other complex features such like a GUI), using something other language like python/ruby/C/rust would be a better tool than shell script. Learning how to choose the appropriate tools to use when solving a problem is an important skills for any engineer.

Shell scripting languages like Bourne (sh) are designed to be a glue language that you use for simple (often interactive) tasks. They are the user interface (or "IDE") of Unix. Asking why shell d9oesn't have built-in support for efficient floating point math or complex GUI features is kind of like asking why Eclipse or Visual Studio don't have a built-in spreadsheet or email client. Yes, you could probably make that happen as a half-assed hack, but it's obviously not the type of task those tools were designed for.

As for the syntax, if you find it confusing or ugly and prefer to use other tools, that's fine. There are a lot of great languages available, so use the tool that is best for you. If it had #!/bin/sh art the top, you can probably substitute any language you prefer without and problems. However, remember that for some of us Bourne shell is the easy, reasonably efficient tool we prefer to use for some problems.

[1] https://en.wikiquote.org/wiki/Pulp_Fiction#Dialogue

[2] https://www.youtube.com/watch?v=sCZJblyT_XM

[3] https://docs.oracle.com/cd/E19957-01/806-3568/ncg_goldberg.h...