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by chubot 435 days ago

??? This complaint seems more than 20 years too late

Arithmetic is built into POSIX shell, and it's universally implemented. The following works in basically every shell, and starts 0 new processes, not 2:

    $ bash -c '[ $((1 + 1)) = 2 ]; echo $?'
    0
    $ zsh -c '[ $((1 + 1)) = 2 ]; echo $?'
    0
    $ busybox ash -c '[ $((1 + 1)) = 2 ]; echo $?'
    0

YSH (part of https://oils.pub/ ) has a more familiar C- or JavaScript-like syntax:

    $ ysh -c 'if (1 + 1 === 2) { echo hi }'
    hi

It also has structured data types like Python or JS:

    $ echo '{"foo": 42}' > test.json
    $ ysh
    ysh-0.28$ json read < test.json
    ysh-0.28$ echo "next = $[_reply.foo + 1]"
    next = 43

and floats, etc.

    $ echo "q = $[_reply.foo / 5]"
    q = 8.4

https://oils.pub/release/latest/doc/ysh-tour.html (It's probably more useful for scripting now, but it's also an interactive shell)

1 comments

DonHopkins 435 days ago

20 years doesn't even get you back to the last century, it's more like 48 years since 1977 when Bourne wrote sh. As one of the authors of the Unix Haters Handbook, published relatively recently in 1994, and someone who's used many versions of Unix since the 1980's, of course I'm fully aware that those problems are hell of a lot more than 20 years old, and that's the whole point: we're still suffering from their "vestigial historic baggage", arcane syntax and semantics originally intended to fork processes and pipe text to solve trivial tasks instead of using shared libraries and machine instructions to perform simple math operations, and people are still trying to justify all that claptrap as the "Unix Philosophy".

Care to explain to me how all the problems of X-Windows have been solved so it's no longer valid to criticize the fallout from its legacy vestigial historic baggage we still suffer from even today? How many decades ago did they first promise the Year of the Linux Desktop?

The X-Windows Disaster: This is Chapter 7 of the UNIX-HATERS Handbook. The X-Windows Disaster chapter was written by Don Hopkins.

https://medium.com/@donhopkins/the-x-windows-disaster-128d39...

Why it took THREE processes and a shitload of context switches and punctuation that we are still stuck with to simply test if 1 + 1 = 2 in classic Unix [TM]:

  [ "$(expr 1 + 1)" -eq 2 ]

Breakdown:

  expr 1 + 1

An external program used to perform arithmetic.

  $(...) (Command substitution)

Runs expr in a subshell to capture its output.

  [ ... ]

In early shells, [ (aka test) was also an external binary.

It took THREE separate processes because:

Unix lacked built-in arithmetic.

The shell couldn't do math.

Even conditionals ([) were external.

Everything was glued together with fragile text and subprocesses.

All of this just to evaluate a single arithmetic expression by ping-ponging in and out of user and kernel space so many times -- despite the CPU being able to do it in a single cycle.

That’s exactly the kind of historical inefficiency the "Unix Philosophy" retroactively romanticizes.