To my eye, this does not look good.

I consider myself to be quite proficient in bash. I write a lot of bash professionally. I've written a compiler (transpiler?) for a strongly typed configuration language that outputs bash.

There are three main problems I see here.

(1) Pipelines, subshells, and external dependencies.

The example on the website compiles a conditional `if age < 18` into this monstrosity:

    if [ $(echo ${__0_age} '<' 18 | bc -l | sed '/\./ s/\.\{0,1\}0\{1,\}$//') != 0 ]

Pipelines and subshells are "slow". Not tremendously. But it adds up. Also, what's the point of having types in your language if you're not going to use native arithmetic when applicable:

    if (( __0_age < 18 ))

Perfectly fine to alert users that floats will require an external dependency (such as dc), but integers will be handled in native arithmetic contexts.

Seems mildly insane that a conditional this simple would require a pipeline including `echo`, `bc`, and `sed`. Now the user needs to ensure the correct external CLI tools are installed, and match the expected versions. Hope they account for BSD vs. GNU variants. Eek.

(2) Namerefs.

> Arrays cannot be nested due to the Bash limitations

Arrays absolutely can be nested... with some trickery. Consider:

    # Top level array w/ pointers to children.
    declare -a arr1=( arr2  arr3 )

    # Child arrays.
    declare -a arr2=( item1  item2 )
    declare -a arr3=( item3  item4 )

    for ref in "${arr1[@]}" ; do
       declare -n sub_array="$ref"
       printf '%s\n' "${sub_array[@]}"
    done

The `declare -n` line is where the magic happens: https://www.gnu.org/software/bash/manual/html_node/Shell-Par...

This is a fairly trivial operation that I'd assume the authors would know about. It's fast and allows for the creation of arbitrarily complex objects. Even rudimentary classes.

(3) Just learn bash.

I'm perpetually confused by people taking every opportunity to not just... learn bash. An otherwise skilled programmer will somehow forget everything they've learned when beginning a shell script.

Surely it can't be harder to learn the fundamentals of shell scripting than to learn whatever flavor-of-the-month alternative is?