Rob Landley is working on implementing a full Bash clone (called toysh[1]) in his Toybox project[2]. I'm excited for it to be released - it will be a huge improvement vs. Busybox ash for embedded environments. We'll be able to write scripts that use arrays!

[1] https://github.com/landley/toybox/blob/master/toys/pending/s...

[2] http://landley.net/toybox/about.html